Publications

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  3D laser imaging for measuring volumetric shrinkage of horticultural products during drying process Mollazade, K.; van der Lucht, J.; Jörissen, S.; Nüchter, A. in Computers and Electronics in Agriculture (2023). 207 107749.
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  The standard method of shrinkage measurement consists of immersion of the product in a fluid in order to calculate the volume changes before and after drying. It is destructive and time-consuming and also is not a practical method to be used in online drying monitoring systems. To date, it has been tried for measuring shrinkage based on passive stereo vision. But no report has been provided so far on the accuracy of this technique and its comparison with conventional method of measuring volumetric shrinkage. On the other hand, because of the small size of dried foodstuff products, it does not seem that the stereo vision to be able to extract high detail point clouds from the surface of objects. Therefore, this research was conducted in order to study the potential use of 3D laser scanning for measurement of the volumetric shrinkage of some horticultural products during drying process. To this end, a calibrated 3D laser imaging system was applied in order to precisely scan the surface of some small size horticultural products (including plum, fig, date, and button mushroom), which take non-symmetric form during the drying process. 2D image of samples was also taken to predict the volumetric shrinkage by various texture analysis methods. Drying was carried out by a convective dryer. The results indicated a significant superiority of 3D laser imaging compared to 2D imaging. The value of correlation coefficient and mean absolute percentage error of multilayer perceptron artificial neural networks models created based on selected spatial features of point clouds in predicting volumetric shrinkage for plum, fig, date, and mushroom was obtained 0.90 and 19.48, 0.95 and 14.25, 0.78 and 23.54, and 0.87 and 9.47, respectively.

  @article{CEAGI2023, abstract = {The standard method of shrinkage measurement consists of immersion of the product in a fluid in order to calculate the volume changes before and after drying. It is destructive and time-consuming and also is not a practical method to be used in online drying monitoring systems. To date, it has been tried for measuring shrinkage based on passive stereo vision. But no report has been provided so far on the accuracy of this technique and its comparison with conventional method of measuring volumetric shrinkage. On the other hand, because of the small size of dried foodstuff products, it does not seem that the stereo vision to be able to extract high detail point clouds from the surface of objects. Therefore, this research was conducted in order to study the potential use of 3D laser scanning for measurement of the volumetric shrinkage of some horticultural products during drying process. To this end, a calibrated 3D laser imaging system was applied in order to precisely scan the surface of some small size horticultural products (including plum, fig, date, and button mushroom), which take non-symmetric form during the drying process. 2D image of samples was also taken to predict the volumetric shrinkage by various texture analysis methods. Drying was carried out by a convective dryer. The results indicated a significant superiority of 3D laser imaging compared to 2D imaging. The value of correlation coefficient and mean absolute percentage error of multilayer perceptron artificial neural networks models created based on selected spatial features of point clouds in predicting volumetric shrinkage for plum, fig, date, and mushroom was obtained 0.90 and 19.48, 0.95 and 14.25, 0.78 and 23.54, and 0.87 and 9.47, respectively.}, author = {Mollazade, K. and van der Lucht, J. and J{\"o}rissen, S. and N{\"u}chter, A.}, journal = {Computers and Electronics in Agriculture}, keywords = {myown}, pages = 107749, title = {3D laser imaging for measuring volumetric shrinkage of horticultural products during drying process}, volume = 207, year = 2023 }
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  Semantic Classification in Uncolored 3D Point Clouds using Multiscale Features Neumann, M.; Borrmann, D.; Nüchter, A. in Proceedings of the 17th Conference on Intelligent Autonomous Systems (IAS ’22), Lecture Notes in Networks and Systems (2023). 342–359.
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  While the semantic segmentation of 2D images is already a well-researched field, the assignment of semantic labels to 3D data is lagging behind. This is partly due to the fact that prelabeled training data is only rarely available since not only the training and application of classification methods but also the manual labeling process are much more time-consuming in 3D. This paper focuses on the more classical approach of first calculating features and subsequently applying a classification algorithm. Existing handcrafted feature definitions are enhanced by using multiple selected reductions of the point cloud as approximations. This serves as input to train a well-studied random forest classifier. A comparison to a recently presented deep learning approach, i.e., the Kernel Point Convolution method, reveals that there are well-justified applications for both modern and classical machine learning methods. To enable the smooth conversion of existing 3D scenes to semantically labeled 3D point clouds the tool \emph{Blender2Helios is presented. We show that the therewith generated artificial data is a good choice for training real-world classifiers.

  @inproceedings{IAS2022, abstract = {While the semantic segmentation of 2D images is already a well-researched field, the assignment of semantic labels to 3D data is lagging behind. This is partly due to the fact that prelabeled training data is only rarely available since not only the training and application of classification methods but also the manual labeling process are much more time-consuming in 3D. This paper focuses on the more classical approach of first calculating features and subsequently applying a classification algorithm. Existing handcrafted feature definitions are enhanced by using multiple selected reductions of the point cloud as approximations. This serves as input to train a well-studied random forest classifier. A comparison to a recently presented deep learning approach, i.e., the Kernel Point Convolution method, reveals that there are well-justified applications for both modern and classical machine learning methods. To enable the smooth conversion of existing 3D scenes to semantically labeled 3D point clouds the tool \emph{Blender2Helios} is presented. We show that the therewith generated artificial data is a good choice for training real-world classifiers.}, address = {Zagreb, Croatia}, author = {Neumann, M. and Borrmann, D. and N{\"u}chter, A.}, booktitle = {Proceedings of the 17th Conference on Intelligent Autonomous Systems (IAS '22)}, keywords = {imported}, month = {June}, number = 577, pages = {342–359}, series = {Lecture Notes in Networks and Systems}, title = {{Semantic Classification in Uncolored 3D Point Clouds using Multiscale Features}}, year = 2023 }
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  Smoothed Normal Distribution Transform for Efficient Point Cloud Registration During Space Rendezvous Renaut, L.; Frei, H.; Nüchter, A. in Proceedings of the 18th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications -- Volume 5: VISAPP, (2023). 919–930.
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  Next to the iterative closest point (ICP) algorithm, the normal distribution transform (NDT) algorithm is be- coming a second standard for 3D point cloud registration in mobile robotics. Both methods are effective, however they require a sufficiently good initialization to successfully converge. In particular, the discontinuities in the NDT cost function can lead to difficulties when performing the optimization. In addition, when the size of the point clouds increases, performing the registration in real-time becomes challenging. This work in- troduces a Gaussian smoothing technique of the NDT map, which can be done prior to the registration process. A kd-tree adaptation of the typical octree representation of NDT maps is also proposed. The performance of the modified smoothed NDT (S-NDT) algorithm for pairwise scan registration is assessed on two large-scale outdoor datasets, and compared to the performance of a state-of-the-art ICP implementation. S-NDT is around four times faster and as robust as ICP while reaching similar precision. The algorithm is thereafter applied to the problem of LiDAR tracking of a spacecraft in close-range in the context of space rendezvous, demonstrating the performance and applicability to real-time applications.

  @inproceedings{VISAPP2023, abstract = {Next to the iterative closest point (ICP) algorithm, the normal distribution transform (NDT) algorithm is be- coming a second standard for 3D point cloud registration in mobile robotics. Both methods are effective, however they require a sufficiently good initialization to successfully converge. In particular, the discontinuities in the NDT cost function can lead to difficulties when performing the optimization. In addition, when the size of the point clouds increases, performing the registration in real-time becomes challenging. This work in- troduces a Gaussian smoothing technique of the NDT map, which can be done prior to the registration process. A kd-tree adaptation of the typical octree representation of NDT maps is also proposed. The performance of the modified smoothed NDT (S-NDT) algorithm for pairwise scan registration is assessed on two large-scale outdoor datasets, and compared to the performance of a state-of-the-art ICP implementation. S-NDT is around four times faster and as robust as ICP while reaching similar precision. The algorithm is thereafter applied to the problem of LiDAR tracking of a spacecraft in close-range in the context of space rendezvous, demonstrating the performance and applicability to real-time applications.}, author = {Renaut, L. and Frei, H. and Nüchter, A.}, booktitle = {Proceedings of the 18th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications – Volume 5: VISAPP,}, keywords = {myown}, organization = {INSTICC}, pages = {919–930}, publisher = {SciTePress}, title = {Smoothed Normal Distribution Transform for Efficient Point Cloud Registration During Space Rendezvous}, year = 2023 }
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  Terrain segmentation for commercial vehicles and working machines Edlinger, R.; Mitterhuber, U.; Nüchter, A. in Proceedings of the IS\&T International Symposium on Electronic Imaging Science and Technology, Electronic Imaging (2023). 324–1.
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  In the field of automated working machines, not only is the general trend towards automation in industry, transport and logistics reflected, but new areas of application and markets are also constantly emerging. In this paper we present a pipeline for terrain classification in offroad environments and in the field of "automated maintenance of slopes", which offers potential for solving numerous socio-economic needs. Working tasks can be made more efficient, more ergonomic and, in particular, much safer, because mature, automated vehicles are used. At present, however, such tasks can only be carried out remotely or semi-automatically, under the supervision of a trained specialist. This only partially facilitates the work. The real benefit only comes when the supervising person is released from this task and is able to pursue other work. In addition to the development of a safe integrated system and sensor concept for use in public spaces as a basic prerequisite for vehicles licensed in the future, increased situational awareness of mobile systems through machine learning in order to increase their efficiency and flexibility is also of great importance.

  @inproceedings{EI2023b, abstract = {In the field of automated working machines, not only is the general trend towards automation in industry, transport and logistics reflected, but new areas of application and markets are also constantly emerging. In this paper we present a pipeline for terrain classification in offroad environments and in the field of "automated maintenance of slopes", which offers potential for solving numerous socio-economic needs. Working tasks can be made more efficient, more ergonomic and, in particular, much safer, because mature, automated vehicles are used. At present, however, such tasks can only be carried out remotely or semi-automatically, under the supervision of a trained specialist. This only partially facilitates the work. The real benefit only comes when the supervising person is released from this task and is able to pursue other work. In addition to the development of a safe integrated system and sensor concept for use in public spaces as a basic prerequisite for vehicles licensed in the future, increased situational awareness of mobile systems through machine learning in order to increase their efficiency and flexibility is also of great importance.}, address = {San Francisco, CA, USA}, author = {Edlinger, R. and Mitterhuber, U. and N{\"u}chter, A.}, booktitle = {Proceedings of the IS\&T International Symposium on Electronic Imaging Science and Technology}, keywords = {imported}, month = {January}, pages = {324-1–324-7}, publisher = {Society for Imaging Science and Technology}, series = {Electronic Imaging}, title = {Terrain segmentation for commercial vehicles and working machines}, year = 2023 }
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  Transfer Learning for LULC Classification on multi-modal data in the Amazon Basin Hell, M.; Brandmeier, M.; and A. Nüchter in Proceedings of the EGU General Assembly 2023 (2023).
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  @inproceedings{EGU2023, address = {Vienna, Austria \& Online}, author = {Hell, M. and Brandmeier, M. and and A. N{\"u}chter}, booktitle = {Proceedings of the EGU General Assembly 2023}, keywords = {author}, month = {April}, number = {EGU2023-15020}, title = {{Transfer Learning for LULC Classification on multi-modal data in the Amazon Basin}}, year = 2023 }
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  Visual odometry and mapping under poor visibility conditions using a stereo infrared thermal imaging system Edlinger, R.; Himmelbauer, G.; Zauner, G.; Nüchter, A. in Proceedings of the IS\&T International Symposium on Electronic Imaging Science and Technology, Electronic Imaging (2023). 325–1.
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  In the past decades, developments in the field of computer vision have made both the software and hardware more capable and more easily accessible. This has enabled otherwise complex vision systems to be used in other fields, such as autonomous robotics. Although vision systems in the visible light spectrum are commonplace in robotics nowadays, the thermal spectrum is still rarely used, even though it offers certain advantages. A thermal camera can sense the temperature of objects, is independent of illumination and can actually see through heavy smoke and fog. This makes it a useful tool in particular in the field of rescue robotics, where poor vision conditions are to be expected. In this paper, the feasibility of using two thermal cameras in a stereo vision setup to map indoor scenes is to be examined. It is meant to allow an autonomous robot to perceive its indoor surroundings as a 3D space, even in poor vision conditions. The biggest challenges are the calibration of thermal cameras and the proper filtering of the raw image and the resulting disparity map. Simple and easily implemented solutions are proposed for each of these issues.

  @inproceedings{EI2023a, abstract = {In the past decades, developments in the field of computer vision have made both the software and hardware more capable and more easily accessible. This has enabled otherwise complex vision systems to be used in other fields, such as autonomous robotics. Although vision systems in the visible light spectrum are commonplace in robotics nowadays, the thermal spectrum is still rarely used, even though it offers certain advantages. A thermal camera can sense the temperature of objects, is independent of illumination and can actually see through heavy smoke and fog. This makes it a useful tool in particular in the field of rescue robotics, where poor vision conditions are to be expected. In this paper, the feasibility of using two thermal cameras in a stereo vision setup to map indoor scenes is to be examined. It is meant to allow an autonomous robot to perceive its indoor surroundings as a 3D space, even in poor vision conditions. The biggest challenges are the calibration of thermal cameras and the proper filtering of the raw image and the resulting disparity map. Simple and easily implemented solutions are proposed for each of these issues.}, address = {San Francisco, CA, USA}, author = {Edlinger, R. and Himmelbauer, G. and Zauner, G. and N{\"u}chter, A.}, booktitle = {Proceedings of the IS\&T International Symposium on Electronic Imaging Science and Technology}, keywords = {imported}, month = {January}, pages = {325-1–325-7}, publisher = {Society for Imaging Science and Technology}, series = {Electronic Imaging}, title = {Visual odometry and mapping under poor visibility conditions using a stereo infrared thermal imaging system}, year = 2023 }

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  Advanced Edge Detection of AprilTags for Precise Docking Maneuvers of Mobile Robots Richter, J.; Bohlig, D.; Nüchter, A.; Schilling, K. in Proceedings of the 6th IFAC Symposium on Telematics Applications (TA ’22) (2022). 117–123.
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  The development of modules and routines into an existing server-based control station to handle approach and docking maneuvers of mobile systems is the central achievement of this work. Efficient material flow in a digitized factory environment requires that goods are automatically loaded and unloaded onto transport robots. For this purpose, accurate positioning of the robot to a loading station is necessary or to a charging station, to automatically charge the robot’s energy storage. Apart from these applications, robots are furthermore increasingly used for assembly work in production facilities. The possibility of using a transport robot as a mobile montage platform at assembly stations with manipulators is investigated in this work. Crucial for this is the ability to repeatedly acquire a position of sub-centimeter accuracy relative to the station and additionally to transmit the precise final position to the station. The critical component here is the estimation of the mobile system’s pose, which is estimated using camera images of artificial markers attached to the stations. Since the precision of a visual localization strongly depends on the detection accuracy of the markers, an optimization problem is formulated to approximate the edges of the markers using an edge model function and thus determine their corners more precisely. Finally, a planar continuous trajectory planning is implemented to determine the segments of a possible path between any two poses.

  @inproceedings{TA2022_1, abstract = {The development of modules and routines into an existing server-based control station to handle approach and docking maneuvers of mobile systems is the central achievement of this work. Efficient material flow in a digitized factory environment requires that goods are automatically loaded and unloaded onto transport robots. For this purpose, accurate positioning of the robot to a loading station is necessary or to a charging station, to automatically charge the robot’s energy storage. Apart from these applications, robots are furthermore increasingly used for assembly work in production facilities. The possibility of using a transport robot as a mobile montage platform at assembly stations with manipulators is investigated in this work. Crucial for this is the ability to repeatedly acquire a position of sub-centimeter accuracy relative to the station and additionally to transmit the precise final position to the station. The critical component here is the estimation of the mobile system’s pose, which is estimated using camera images of artificial markers attached to the stations. Since the precision of a visual localization strongly depends on the detection accuracy of the markers, an optimization problem is formulated to approximate the edges of the markers using an edge model function and thus determine their corners more precisely. Finally, a planar continuous trajectory planning is implemented to determine the segments of a possible path between any two poses.}, address = {Nancy, France}, author = {Richter, J. and Bohlig, D. and N{\"u}chter, A. and Schilling, K.}, booktitle = {Proceedings of the 6th IFAC Symposium on Telematics Applications (TA '22)}, keywords = {imported}, month = {June}, pages = {117-123}, title = {{Advanced Edge Detection of AprilTags for Precise Docking Maneuvers of Mobile Robots}}, year = 2022 }
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  Advances in Mobile Mapping Technologies Lehtola, V.; Nüchter, A.; Goulette, F. in (This book is a printed edition of the Special Issue Advances in Mobile Mapping Technologies that was published in Remote Sensing) (2022). MDPI, Basel, Switzerland.
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  Mobile mapping is applied widely in society, for example, in asset management, fleet management, construction planning, road safety, and maintenance optimization. Yet, further advances in these technologies are called for. Advances can be radical, such as changes to the prevailing paradigms in mobile mapping, or incremental, such as the state-of-the-art mobile mapping methods. With current multi-sensor systems in mobile mapping, laser-scanned data are often registered in point clouds with the aid of global navigation satellite system (GNSS) positioning or simultaneous localization and mapping (SLAM) techniques and then labeled and colored with the aid of machine learning methods and digital camera data. These multi-sensor platforms are beginning to undergo further advancements via the addition of multi-spectral and other sensors and via the development of machine learning techniques used in processing this multi-modal data. Embedded systems and minimalistic system designs are also attracting attention, from both academic and commercial perspectives. In order to address these topics, we edited the Special Issue Advances in Mobile Mapping Technologies for the Remote Sensing journal. This book contains the published articles of this Special Issue and is aimed at those in academia and industry alike. Specifically, it consists of works introducing a new mobile mapping dataset (‘Paris CARLA 3D’), system calibration studies, SLAM topics, and multiple deep learning works for asset detection. We wish to thank all the authors who contributed to this collection.

  @book{MDPISENSORS2022, abstract = {Mobile mapping is applied widely in society, for example, in asset management, fleet management, construction planning, road safety, and maintenance optimization. Yet, further advances in these technologies are called for. Advances can be radical, such as changes to the prevailing paradigms in mobile mapping, or incremental, such as the state-of-the-art mobile mapping methods. With current multi-sensor systems in mobile mapping, laser-scanned data are often registered in point clouds with the aid of global navigation satellite system (GNSS) positioning or simultaneous localization and mapping (SLAM) techniques and then labeled and colored with the aid of machine learning methods and digital camera data. These multi-sensor platforms are beginning to undergo further advancements via the addition of multi-spectral and other sensors and via the development of machine learning techniques used in processing this multi-modal data. Embedded systems and minimalistic system designs are also attracting attention, from both academic and commercial perspectives. In order to address these topics, we edited the Special Issue Advances in Mobile Mapping Technologies for the Remote Sensing journal. This book contains the published articles of this Special Issue and is aimed at those in academia and industry alike. Specifically, it consists of works introducing a new mobile mapping dataset (‘Paris CARLA 3D’), system calibration studies, SLAM topics, and multiple deep learning works for asset detection. We wish to thank all the authors who contributed to this collection.}, address = {Basel, Switzerland}, editor = {Lehtola, V. and N{\"u}chter, A. and Goulette, F.}, keywords = {myown}, month = {March}, publisher = {MDPI}, series = {(This book is a printed edition of the Special Issue Advances in Mobile Mapping Technologies that was published in Remote Sensing)}, title = {Advances in Mobile Mapping Technologies}, year = 2022 }
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  Aerial 3D Mapping with Continuous Time ICP for Urban Search and Rescue Lauterbach, H. A.; Nüchter, A. in Autonomous Mobile Mapping Robots, J. B\ce}}dkowski (ed.) (2022).
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  Fast reconnaissance is essential for strategic decisions during the immediate response phase of urban search and rescue missions. Nowadays, UAVs with their advantageous overview perspective are increasingly used for reconnaissance besides manual inspection of the scenario. However, data evaluation is often limited to visual inspection of images or video footage. We present our LiDAR-based aerial 3D map- ping system, providing real-time maps of the environment. UAV-borne laser scans typically offer a reduced field of view. Moreover, UAV trajectories are more flexible and dynamic compared to those of ground vehicles, for which SLAM systems are often designed. We address these challenges by a two-step registration approach based on continuous time ICP. The experiments show that the resulting maps accu- rately represent the environment.

  @incollection{INTECH22B, abstract = {Fast reconnaissance is essential for strategic decisions during the immediate response phase of urban search and rescue missions. Nowadays, UAVs with their advantageous overview perspective are increasingly used for reconnaissance besides manual inspection of the scenario. However, data evaluation is often limited to visual inspection of images or video footage. We present our LiDAR-based aerial 3D map- ping system, providing real-time maps of the environment. UAV-borne laser scans typically offer a reduced field of view. Moreover, UAV trajectories are more flexible and dynamic compared to those of ground vehicles, for which SLAM systems are often designed. We address these challenges by a two-step registration approach based on continuous time ICP. The experiments show that the resulting maps accu- rately represent the environment.}, address = {Rijeka, Croatia}, author = {Lauterbach, H. A. and N{\"u}chter, A.}, booktitle = {{A}utonomous {M}obile {M}apping {R}obots}, chapter = 6, editor = {B{\c{e}}dkowski, Janusz}, keywords = {imported}, publisher = {IntechOpen}, title = {{A}erial {3D} {M}apping with {C}ontinuous {T}ime {ICP} for {U}rban {S}earch and {R}escue}, year = 2022 }
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  AI supported Multi-Functional Gripping System for Dexterous Manipulation Tasks Edlinger, R.; Föls, C.; Mitterhuber, U.; Nüchter, A. in Proceedings of the IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’22) (2022). 145–152.
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  Dexterous mobile manipulators that are capable of performing a wide array of tasks are essential for unstructured human-centered environments. Especially in rescue scenarios where time and resources are limited, a gripping system should be as versatile but at the same time as efficient as possible. In addition, situational awareness in accidents and impaired visibility is essential for safely performing missions or automating behaviors, and thus supporting operators. The main contribution of this work is a multi-functional gripping system with technologies and methods for manipulation in rescue and recovery operations as well as for handling hazardous materials. The gripping system is supplemented by an RGB and thermal camera and object detection algorithms, which run in real-time on an embedded device for robust recognition in harsh and dynamic environments. The proposed multi-functional gripping system has been thoroughly evaluated and tested in laboratory experiments and real field facilities.

  @inproceedings{SSRR2022_2, abstract = {Dexterous mobile manipulators that are capable of performing a wide array of tasks are essential for unstructured human-centered environments. Especially in rescue scenarios where time and resources are limited, a gripping system should be as versatile but at the same time as efficient as possible. In addition, situational awareness in accidents and impaired visibility is essential for safely performing missions or automating behaviors, and thus supporting operators. The main contribution of this work is a multi-functional gripping system with technologies and methods for manipulation in rescue and recovery operations as well as for handling hazardous materials. The gripping system is supplemented by an RGB and thermal camera and object detection algorithms, which run in real-time on an embedded device for robust recognition in harsh and dynamic environments. The proposed multi-functional gripping system has been thoroughly evaluated and tested in laboratory experiments and real field facilities.}, address = {Seville, Spain}, author = {Edlinger, R. and F{\"o}ls, C. and Mitterhuber, U. and N{\"u}chter, A.}, booktitle = {Proceedings of the IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '22)}, keywords = {imported}, month = {November}, pages = {145–152}, title = {{AI supported Multi-Functional Gripping System for Dexterous Manipulation Tasks}}, year = 2022 }
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  An Algorithm for the SE(3)-Transformation on Neural Implicit Maps for Remapping Functions Yuan, Y.; Nüchter, A. in IEEE Robotics and Automation Letters (RAL) (2022). 7(3) 7763–7770.
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  Implicit representations are widely used for object reconstruction due their efficiency and flexibility. In 2021, a novel structure named neural implicit map has been invented for incremental reconstruction. A neural implicit map alleviates the problem of inefficient memory cost of previous online 3D dense reconstruction while producing better quality. However, the neural implicit map suffers the limitations that it does not support remapping as the frames of scans are encoded into a deep prior after generating the neural implicit map. This means, neither this generation process is invertible, nor a deep prior is transformable. The non-remappable property makes it not possible to apply loop-closure techniques. We present an implicit-map based transformation algorithm to fill this gap. As our implicit-map is transformable, our model supports remapping for this special map of latent features. Experiments show that our remapping module is capable to well-transform neural implicit maps to new poses. Embedded into a SLAM framework, our mapping model is able to tackle remapping of loop-closures and demonstrates high-quality surface reconstruction. Our implementation is available at github (https://github.com/Jarrome/IMT_Mapping) for the research community.

  @article{RAL2022_2, abstract = {Implicit representations are widely used for object reconstruction due their efficiency and flexibility. In 2021, a novel structure named neural implicit map has been invented for incremental reconstruction. A neural implicit map alleviates the problem of inefficient memory cost of previous online 3D dense reconstruction while producing better quality. However, the neural implicit map suffers the limitations that it does not support remapping as the frames of scans are encoded into a deep prior after generating the neural implicit map. This means, neither this generation process is invertible, nor a deep prior is transformable. The non-remappable property makes it not possible to apply loop-closure techniques. We present an implicit-map based transformation algorithm to fill this gap. As our implicit-map is transformable, our model supports remapping for this special map of latent features. Experiments show that our remapping module is capable to well-transform neural implicit maps to new poses. Embedded into a SLAM framework, our mapping model is able to tackle remapping of loop-closures and demonstrates high-quality surface reconstruction. Our implementation is available at github (https://github.com/Jarrome/IMT_Mapping) for the research community.}, author = {Yuan, Y. and N{\"u}chter, A.}, journal = {IEEE Robotics and Automation Letters (RAL)}, keywords = {myown}, month = {July}, number = 3, pages = {7763–7770}, title = {{An Algorithm for the SE(3)-Transformation on Neural Implicit Maps for Remapping Functions}}, volume = 7, year = 2022 }
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  An approach for monitoring temperature on fruit surface by means of thermal point cloud Tsoulias, N.; Jörissen, S.; Nüchter, A. in MethodsX (2022). 9 101712.
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  Heat and excessive solar radiation can produce abiotic stresses during apple maturation, resulting fruit quality. Therefore, the monitoring of temperature on fruit surface (FST) over the growing period can allow to identify thresholds, above of which several physiological disorders such as sunburn may occur in apple. The current approaches neglect spatial variation of FST and have reduced repeatability, resulting in unreliable predictions. In this study, LiDAR laser scanning and thermal imaging were employed to detect the temperature on fruit surface by means of 3D point cloud. A process for calibrating the two sensors based on an active board target and producing a 3D thermal point cloud was suggested. After calibration, the sensor system was utilised to scan the fruit trees, while temperature values assigned in the corresponding 3D point cloud were based on the extrinsic calibration. Whereas a fruit detection algorithm was performed in order to segment the FST from each apple.•The approach allows the calibration of LiDAR laser scanner with thermal camera in order to produce a 3D thermal point cloud.•The method can be applied in apple trees for segmenting FST in 3D. Whereas the approach can be utilised to predict several physiological disorders including sunburn on fruit surface.

  @article{METHODSX2022, abstract = {Heat and excessive solar radiation can produce abiotic stresses during apple maturation, resulting fruit quality. Therefore, the monitoring of temperature on fruit surface (FST) over the growing period can allow to identify thresholds, above of which several physiological disorders such as sunburn may occur in apple. The current approaches neglect spatial variation of FST and have reduced repeatability, resulting in unreliable predictions. In this study, LiDAR laser scanning and thermal imaging were employed to detect the temperature on fruit surface by means of 3D point cloud. A process for calibrating the two sensors based on an active board target and producing a 3D thermal point cloud was suggested. After calibration, the sensor system was utilised to scan the fruit trees, while temperature values assigned in the corresponding 3D point cloud were based on the extrinsic calibration. Whereas a fruit detection algorithm was performed in order to segment the FST from each apple.•The approach allows the calibration of LiDAR laser scanner with thermal camera in order to produce a 3D thermal point cloud.•The method can be applied in apple trees for segmenting FST in 3D. Whereas the approach can be utilised to predict several physiological disorders including sunburn on fruit surface.}, author = {Tsoulias, N. and Jörissen, S. and N{\"u}chter, A.}, journal = {MethodsX}, keywords = {myown}, pages = 101712, title = {An approach for monitoring temperature on fruit surface by means of thermal point cloud}, volume = 9, year = 2022 }
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  An innovative pick-up and transport robot system for casualty evacuation Edlinger, R.; Föls, C.; Nüchter, A. in Proceedings of the IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’22) (2022). 67–73.
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  This paper addresses the search and rescue scenario Casualty Evacuation (CasEvac) at the European Land Robot Trial (ELROB). A disaster response robot can be sent into areas to rescue victims where it is too dangerous for human rescue due to environmental issues like the danger of collapse or radioactivity. If injured persons are no longer able to move, the robot must be able to rescue them from the danger zone. This paper addresses this scenario and describes our system design, the manipulator tool and the innovative control mechanism for transporting victims. The experiment was tested at the competition and compared with other solutions from the participating teams and currently implemented developments.

  @inproceedings{SSRR2022_1, abstract = {This paper addresses the search and rescue scenario Casualty Evacuation (CasEvac) at the European Land Robot Trial (ELROB). A disaster response robot can be sent into areas to rescue victims where it is too dangerous for human rescue due to environmental issues like the danger of collapse or radioactivity. If injured persons are no longer able to move, the robot must be able to rescue them from the danger zone. This paper addresses this scenario and describes our system design, the manipulator tool and the innovative control mechanism for transporting victims. The experiment was tested at the competition and compared with other solutions from the participating teams and currently implemented developments.}, address = {Seville, Spain}, author = {Edlinger, R. and F{\"o}ls, C. and N{\"u}chter, A.}, booktitle = {Proceedings of the IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '22)}, keywords = {imported}, month = {November}, pages = {67–73}, title = {{A}n innovative pick-up and transport robot system for casualty evacuation}, year = 2022 }
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  Door Pose Estimation and Robot Positioning for Autonomous Door Opening Mitterhuber, U.; Edlinger, R.; Froschauer, R.; Nüchter, A. in Proceedings of the Autrian Robotics Workshop (ARW ’22), M. Brandstötter, G. Steinbauer-Wagner, J. Piater, and L.-M. Faller (eds.) (2022). 36–41.
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  For autonomous robots to deliver value in human centered environments, they must be able to autonomously open doors. For doing so, they have to overcome multiple challenges, one of which is, to estimate the desired door’s orientation and position. The information if the door handle is on the left or right side of the door must also be obtained. In this work, a novel method, solving the stated problems is proposed. It’s perception is based on a sensor fusion of a monocular camera based state-of-the-art deep learning object detection algorithm with a 2D laser scan and subsequent line estimation. Additionally, a differential drive controller, using the advancement of continuous goal pose updating, is proposed. During real-world experimentation with a differential drive robot, the implemented system was able to position the robot in front of a door every time with sufficient accuracy and is thus found to solve the stated problem successfully.

  @inproceedings{ARW2022_1, abstract = {For autonomous robots to deliver value in human centered environments, they must be able to autonomously open doors. For doing so, they have to overcome multiple challenges, one of which is, to estimate the desired door’s orientation and position. The information if the door handle is on the left or right side of the door must also be obtained. In this work, a novel method, solving the stated problems is proposed. It’s perception is based on a sensor fusion of a monocular camera based state-of-the-art deep learning object detection algorithm with a 2D laser scan and subsequent line estimation. Additionally, a differential drive controller, using the advancement of continuous goal pose updating, is proposed. During real-world experimentation with a differential drive robot, the implemented system was able to position the robot in front of a door every time with sufficient accuracy and is thus found to solve the stated problem successfully.}, address = {Villach, Austria}, author = {Mitterhuber, U. and Edlinger, R. and Froschauer, R. and N{\"u}chter, A.}, booktitle = {Proceedings of the Autrian Robotics Workshop (ARW '22)}, editor = {Brandst{\"o}tter, M. and Steinbauer-Wagner, G. and Piater, J. and and L.-M. Faller}, keywords = {imported}, month = {June}, pages = {36–41}, title = {Door Pose Estimation and Robot Positioning for Autonomous Door Opening}, year = 2022 }
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  Dynamic Point Cloud Compression Based on Projections, Surface Reconstruction and Video Compression Dumic, E.; Bjelopera, A.; Nüchter, A. in Sensors (2022). 22(1)
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  In this paper we will present a new dynamic point cloud compression based on different projection types and bit depth, combined with the surface reconstruction algorithm and video compression for obtained geometry and texture maps. Texture maps have been compressed after creating Voronoi diagrams. Used video compression is specific for geometry (FFV1) and texture (H.265/HEVC). Decompressed point clouds are reconstructed using a Poisson surface reconstruction algorithm. Comparison with the original point clouds was performed using point-to-point and point-to-plane measures. Comprehensive experiments show better performance for some projection maps: cylindrical, Miller and Mercator projections.

  @article{MDPI2022, abstract = {In this paper we will present a new dynamic point cloud compression based on different projection types and bit depth, combined with the surface reconstruction algorithm and video compression for obtained geometry and texture maps. Texture maps have been compressed after creating Voronoi diagrams. Used video compression is specific for geometry (FFV1) and texture (H.265/HEVC). Decompressed point clouds are reconstructed using a Poisson surface reconstruction algorithm. Comparison with the original point clouds was performed using point-to-point and point-to-plane measures. Comprehensive experiments show better performance for some projection maps: cylindrical, Miller and Mercator projections.}, author = {Dumic, E. and Bjelopera, A. and N{\"u}chter, A.}, journal = {Sensors}, keywords = {imported}, number = 1, title = {{Dynamic Point Cloud Compression Based on Projections, Surface Reconstruction and Video Compression}}, volume = 22, year = 2022 }
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  Entwicklung einer randomisierten Hough-Transformation zur Zylinderdetektion in Laserscans Menninger, S.; Bleier, and M.; Nüchter, A. in Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beiträge der Oldenburger 3D-Tage 2022, Jade Hochschule (2022). 260–267.
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  Neben Ebenen sind Zylinder eine der am häufigsten auftretenden grundlegenden Formen im industriellen Bereich, da sie als geometrische Primitive für Rohrleitungen, Gerüste und dergleichen dienen. Eine schnelle, effiziente und robuste Methode zur Detektion von Zylindern in Punktwolken ist somit essenziell, um die manuellen Schritte bei der Modellerzeugung zu minimieren. Auch wenn es möglich ist, mithilfe einer 5D Hough-Transformation Zylinder zu detektieren, so ist dieser Ansatz doch sehr komplex und zeitintensiv. Aus diesem Grund ist diese Methode auf großen Punktwolken nicht direkt anwendbar. Eine Verringerung der Komplexität kann durch einen sequenziellen zwei Schritt Ansatz ermöglicht werden. Der erste Schritt findet mithilfe einer 2D-Hough-Transformation eine starke Hypothese für die Zylinderachsenorientierung, während sich der Zweite mit der Suche des Radius und der Zylinderposition im dreidimensionalen Raum beschäftigt. Die vorliegende Arbeit stellt eine Randomized Hough-Transformation (RHT) basierte Implementierung vor, die sich damit beschäftigt, möglichst effizient Zylinder und Teilzylinder bis hin zu Halbzylindern automatisch zu detektieren. Mithilfe Simulations- sowie Echtdaten werden die Resultate anschließend verifiziert und bewertet.

  @inproceedings{3DTAGE2022_1, abstract = {Neben Ebenen sind Zylinder eine der am häufigsten auftretenden grundlegenden Formen im industriellen Bereich, da sie als geometrische Primitive für Rohrleitungen, Gerüste und dergleichen dienen. Eine schnelle, effiziente und robuste Methode zur Detektion von Zylindern in Punktwolken ist somit essenziell, um die manuellen Schritte bei der Modellerzeugung zu minimieren. Auch wenn es möglich ist, mithilfe einer 5D Hough-Transformation Zylinder zu detektieren, so ist dieser Ansatz doch sehr komplex und zeitintensiv. Aus diesem Grund ist diese Methode auf großen Punktwolken nicht direkt anwendbar. Eine Verringerung der Komplexität kann durch einen sequenziellen zwei Schritt Ansatz ermöglicht werden. Der erste Schritt findet mithilfe einer 2D-Hough-Transformation eine starke Hypothese für die Zylinderachsenorientierung, während sich der Zweite mit der Suche des Radius und der Zylinderposition im dreidimensionalen Raum beschäftigt. Die vorliegende Arbeit stellt eine Randomized Hough-Transformation (RHT) basierte Implementierung vor, die sich damit beschäftigt, möglichst effizient Zylinder und Teilzylinder bis hin zu Halbzylindern automatisch zu detektieren. Mithilfe Simulations- sowie Echtdaten werden die Resultate anschließend verifiziert und bewertet.}, author = {Menninger, S. and and M. Bleier and N{\"u}chter, A.}, booktitle = {Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beitr{\"a}ge der Oldenburger 3D-Tage 2022, Jade Hochschule}, keywords = {imported}, month = {February}, pages = {260–267}, publisher = {Wichmann}, title = {{Entwicklung einer randomisierten Hough-Transformation zur Zylinderdetektion in Laserscans}}, year = 2022 }
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  Field Experiments with an Automated Utility Platform for Transportation and Work Processes Edlinger, R.; Dumberger, S.; Froschauer, R.; Pointner, W.; Zeilinger, M.; Nüchter, A. in Proceedings of the IEEE International Conference on Autonomous Robot Systems and Competitions (ICARSC ’22) (2022). 21–26.
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  The automation of transport and work tasks in various application domains continues to be a major challenge. The proposed paper presents key technologies within a process from sensing to reasoning and includes: (i) understanding the scene and its relations through new approaches in object classification and pose estimation based on machine learning, as well as methods for reliable detection of objects and object features; (ii) reliable and safe outdoor localization and mapping based on multi-modal approaches and innovative camera-based methods. The fusion of different sensor data is used for reliable obstacle detection and collision avoidance. The investigation of suitable system architectures, data processing platforms and communication mechanisms taking into account safety requirements is a prerequisite for the operation in a safety-critical environment. The paper provides a proof of concept for an automated platform to demonstrate and evaluate application scenario provided by the Linz Airport in the form of an automated transport process for air freight between a terminal and the aircraft.

  @inproceedings{ICARSC2022_2, abstract = {The automation of transport and work tasks in various application domains continues to be a major challenge. The proposed paper presents key technologies within a process from sensing to reasoning and includes: (i) understanding the scene and its relations through new approaches in object classification and pose estimation based on machine learning, as well as methods for reliable detection of objects and object features; (ii) reliable and safe outdoor localization and mapping based on multi-modal approaches and innovative camera-based methods. The fusion of different sensor data is used for reliable obstacle detection and collision avoidance. The investigation of suitable system architectures, data processing platforms and communication mechanisms taking into account safety requirements is a prerequisite for the operation in a safety-critical environment. The paper provides a proof of concept for an automated platform to demonstrate and evaluate application scenario provided by the Linz Airport in the form of an automated transport process for air freight between a terminal and the aircraft.}, address = {Santa Maria da Feira, Portugal}, author = {Edlinger, R. and Dumberger, S. and Froschauer, R. and Pointner, W. and Zeilinger, M. and N{\"u}chter, A.}, booktitle = {Proceedings of the IEEE International Conference on Autonomous Robot Systems and Competitions (ICARSC '22)}, keywords = {myown}, month = {April}, pages = {21–26}, title = {{Field Experiments with an Automated Utility Platform for Transportation and Work Processes}}, year = 2022 }
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  Finding and Following Optimal Trajectories for an Overactuated Floating Robotic Platform Bredenbeck, A.; Vyas, S.; Suter, W.; Zwick, M.; Borrmann, D.; Olivares-Mendez, M.; Nüchter, A. in 16th Symposium on Advanced Space Technologies in Robotics and Automation (ASTRA ’22) (2022).
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  The recent increase in yearly spacecraft launches and the high number of planned launches have raised questions about maintaining accessibility to space for all interested parties. A key to sustaining the future of space-flight is the ability to service malfunctioning - and actively remove dysfunctional spacecraft from orbit. Robotic platforms that autonomously perform these tasks are a topic of ongoing research and thus must undergo thorough testing before launch. For representative system-level testing, the European Space Agency (ESA) uses, among other things, the Orbital Robotics and GNC Lab (ORGL), a flat-floor facility where air-bearing based platforms exhibit free-floating behavior in three Degrees of Freedom (DoF). This work introduces a representative simulation of a free-floating platform in the testing environment and a software framework for controller development. Finally, this work proposes a controller within that framework for finding and following optimal trajectories between arbitrary states, which is evaluated in simulation and reality.

  @inproceedings{ASTRA2022, abstract = {The recent increase in yearly spacecraft launches and the high number of planned launches have raised questions about maintaining accessibility to space for all interested parties. A key to sustaining the future of space-flight is the ability to service malfunctioning - and actively remove dysfunctional spacecraft from orbit. Robotic platforms that autonomously perform these tasks are a topic of ongoing research and thus must undergo thorough testing before launch. For representative system-level testing, the European Space Agency (ESA) uses, among other things, the Orbital Robotics and GNC Lab (ORGL), a flat-floor facility where air-bearing based platforms exhibit free-floating behavior in three Degrees of Freedom (DoF). This work introduces a representative simulation of a free-floating platform in the testing environment and a software framework for controller development. Finally, this work proposes a controller within that framework for finding and following optimal trajectories between arbitrary states, which is evaluated in simulation and reality.}, address = {Noordwijk, Netherlands}, author = {Bredenbeck, A. and Vyas, S. and Suter, W. and Zwick, M. and Borrmann, D. and Olivares-Mendez, M. and N{\"u}chter, A.}, booktitle = {16th Symposium on Advanced Space Technologies in Robotics and Automation (ASTRA '22)}, keywords = {myown}, month = {June}, publisher = {ESA}, title = {{Finding and Following Optimal Trajectories for an Overactuated Floating Robotic Platform}}, year = 2022 }
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  Indirect Point Cloud Registration: Aligning Distance Fields Using a Pseudo Third Point Set Yuan, Y.; Nüchter, A. in IEEE Robotics and Automation Letters (RAL) (2022). 7(3) 7075–7082.
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  In recent years, implicit functions have drawn attention in the field of 3D reconstruction and have successfully been applied with Deep Learning. However, for incremental reconstruction, implicit function-based registrations have been rarely explored. Inspired by the high precision of deep learning global feature registration, we propose to combine this with distance fields. We generalize the algorithm to a non-Deep Learning setting while retaining the accuracy. Our algorithm is more accurate than conventional models while, without any training, it achieves a competitive performance and faster speed, compared to Deep Learning-based registration models. The implementation is available on github for the research community.

  @article{RAL2022_1, abstract = {In recent years, implicit functions have drawn attention in the field of 3D reconstruction and have successfully been applied with Deep Learning. However, for incremental reconstruction, implicit function-based registrations have been rarely explored. Inspired by the high precision of deep learning global feature registration, we propose to combine this with distance fields. We generalize the algorithm to a non-Deep Learning setting while retaining the accuracy. Our algorithm is more accurate than conventional models while, without any training, it achieves a competitive performance and faster speed, compared to Deep Learning-based registration models. The implementation is available on github for the research community.}, author = {Yuan, Y. and N{\"u}chter, A.}, journal = {IEEE Robotics and Automation Letters (RAL)}, keywords = {myown}, number = 3, pages = {7075–7082}, title = {{Indirect Point Cloud Registration: Aligning Distance Fields Using a Pseudo Third Point Set}}, volume = 7, year = 2022 }
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  KINECT BACKPACK FOR RAPID MOBILE INDOOR MAPPING Bleier, M.; van der Lucht, J.; Nüchter, A. in Proceedings of the ISPRS Congress 2022, ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences (2022). 121–127.
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  In recent years, 3D surveying using mobile mapping has become increasingly popular. Handheld or backpack mounted systems resulted in new uses and applications because they enable fast data acquisition in areas that are difficult to access. Many of these applications do not require high-precision measurement, but they often involve highly complex environments. In this paper, we present a mobile mapping backpack based on four Microsoft Kinect RGB-D sensors and an Intel T265 tracking camera. The data processing takes place in three steps. Starting with a first trajectory and map created using visual-inertial odometry, which is subsequently optimized by means of a continuous-time ICP. Finally, the trajectory is further improved by a continuous-time SLAM approach. In this work, a data set was recorded and analyzed in a bunker facility with the system carried at a walking speed of approximately 0.7 meters per second. For the evaluation, these data are compared with a reference data set, recorded with a Riegl VZ-400 laser scanner.

  @inproceedings{ISPRSCongress2022, abstract = {In recent years, 3D surveying using mobile mapping has become increasingly popular. Handheld or backpack mounted systems resulted in new uses and applications because they enable fast data acquisition in areas that are difficult to access. Many of these applications do not require high-precision measurement, but they often involve highly complex environments. In this paper, we present a mobile mapping backpack based on four Microsoft Kinect RGB-D sensors and an Intel T265 tracking camera. The data processing takes place in three steps. Starting with a first trajectory and map created using visual-inertial odometry, which is subsequently optimized by means of a continuous-time ICP. Finally, the trajectory is further improved by a continuous-time SLAM approach. In this work, a data set was recorded and analyzed in a bunker facility with the system carried at a walking speed of approximately 0.7 meters per second. For the evaluation, these data are compared with a reference data set, recorded with a Riegl VZ-400 laser scanner.}, address = {Nice, France}, author = {Bleier, M. and van der Lucht, J. and N{\"u}chter, A.}, booktitle = {Proceedings of the ISPRS Congress 2022}, keywords = {myown}, number = {V-1-2022}, pages = {121–127}, series = {ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences}, title = {{KINECT BACKPACK FOR RAPID MOBILE INDOOR MAPPING}}, year = 2022 }
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  Melt Electrowriting of Poly(dioxanone) Filament Using a Multi-Axis Robot Luposchainsky, S.; Jörissen, S.; Nüchter, A.; Dalton, P. D. in Macromolecular Materials and Engineering (2022). 2200450.
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  Abstract Excessive thermal degradation is one limitation of scaffold production by melt electrowriting (MEW). This is particularly pertinent when using higher melting point polymers with faster degradation profiles in vivo for tissue engineering applications. This is addressed here by switching from a pneumatic to a filament-based feeding system and demonstrating the processing of a medical polymer, poly(dioxanone) (PDO). Additionally, by replacing the established cartesian printer configuration with a six-axis robotic arm, arbitrary nonplanar surfaces can be used as a fiber collector, as shown here by using a spherical collector. The combination of these techniques allows MEW to be used more broadly in tissue engineering where currently established medical polymers are incompatible with the process, or the geometric shapes of scaffold are to be expanded. It demonstrates the required technology to produce nonplanar scaffolds of PDO in a dome shape with dimensions for a biodegradable corneal implant.

  @article{MACROENG2022, abstract = {Abstract Excessive thermal degradation is one limitation of scaffold production by melt electrowriting (MEW). This is particularly pertinent when using higher melting point polymers with faster degradation profiles in vivo for tissue engineering applications. This is addressed here by switching from a pneumatic to a filament-based feeding system and demonstrating the processing of a medical polymer, poly(dioxanone) (PDO). Additionally, by replacing the established cartesian printer configuration with a six-axis robotic arm, arbitrary nonplanar surfaces can be used as a fiber collector, as shown here by using a spherical collector. The combination of these techniques allows MEW to be used more broadly in tissue engineering where currently established medical polymers are incompatible with the process, or the geometric shapes of scaffold are to be expanded. It demonstrates the required technology to produce nonplanar scaffolds of PDO in a dome shape with dimensions for a biodegradable corneal implant.}, author = {Luposchainsky, S. and Jörissen, S. and N{\"u}chter, A. and Dalton, P. D.}, journal = {Macromolecular Materials and Engineering}, keywords = {imported}, month = {October}, pages = 2200450, title = {{M}elt {E}lectrowriting of {Poly(dioxanone)} {F}ilament {U}sing a {M}ulti-{A}xis {R}obot}, year = 2022 }
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  Mobile 3D scanning and mapping for freely rotating and vertically descended LiDAR Arzberger, F.; Zevering, J.; Bredenbeck, A.; Borrmann, D.; Nüchter, A. in Proceedings of the IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’22) (2022). 122–129.
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  Situational awareness in search and rescue missions is key to successful operations, e.g., in collapsed buildings, underground mine shafts, construction sites, and underwater caves. LiDAR sensors in robotics play an increasingly important role in this context, as do robust and application-specific algorithms for simultaneous localization and mapping (SLAM). In many of these scenarios mapping requires the utilization of a vertically descended scanning system. This work presents a mobile system designed to solve this task, including a SLAM approach for descended LiDAR sensors with small field of view (FoV), which are in uncontrolled rotation. The SLAM approach is based on planar polygon matching and is not limited to the presented scenario. We test the system by lowering it from a crane inside a tall building at a fire-fighter school, applying our offline SLAM approach, and comparing the resulting point clouds of the environment with ground truth maps acquired by a terrestrial laser scanner (TLS). We also compare the SLAM approach to a state-of-the-art approach with respect to runtime and accuracy of the resulting maps. Our solution achieves comparable mapping accuracy at 0.2 of the runtime

  @inproceedings{SSRR2022, abstract = {Situational awareness in search and rescue missions is key to successful operations, e.g., in collapsed buildings, underground mine shafts, construction sites, and underwater caves. LiDAR sensors in robotics play an increasingly important role in this context, as do robust and application-specific algorithms for simultaneous localization and mapping (SLAM). In many of these scenarios mapping requires the utilization of a vertically descended scanning system. This work presents a mobile system designed to solve this task, including a SLAM approach for descended LiDAR sensors with small field of view (FoV), which are in uncontrolled rotation. The SLAM approach is based on planar polygon matching and is not limited to the presented scenario. We test the system by lowering it from a crane inside a tall building at a fire-fighter school, applying our offline SLAM approach, and comparing the resulting point clouds of the environment with ground truth maps acquired by a terrestrial laser scanner (TLS). We also compare the SLAM approach to a state-of-the-art approach with respect to runtime and accuracy of the resulting maps. Our solution achieves comparable mapping accuracy at 0.2 of the runtime}, address = {Seville, Spain}, author = {Arzberger, F. and Zevering, J. and Bredenbeck, A. and Borrmann, D. and N{\"u}chter, A.}, booktitle = {Proceedings of the IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '22)}, keywords = {imported}, pages = {122–129}, title = {{M}obile 3D scanning and mapping for freely rotating and vertically descended {LiDAR}}, year = 2022 }
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  Modular HRI Approach with reliable and resilient wireless communication for rescue robots and first responders Edlinger, R.; Anschober, M.; Froschauer, R.; Nüchter, A. in 31st IEEE International Conference on Robot and Human Interactive Communication (RO-MAN’22) (2022).
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  In this paper, we present a user-selectable con- trol unit to make complex robot systems easier to operate. The robots are primarily used for obtaining information and manipulating dangerous objects or support emergency forces in dealing with crisis situations. Based on hazardous mission scenarios in which mobile robot systems are confronted with complex manipulation and maneuvering tasks (e.g., leakage of contaminants), new methods and concepts in the area of robot decision making, sensor data presentation and control concepts were developed to facilitate the handling and operation of assistance robots. The flexibility of the control concept approach is intended to increase the confidence of the emergency services and to provide intuitive operation of the assistance robots for every user. An intuitive control and stable communication for both control commands and feedback from the robot itself increase trust in the robotic system and its acceptance by the operators. These developments have been investigated in field trials with different types of robots and with network communication constraints.

  @inproceedings{ROMAN2022, abstract = {In this paper, we present a user-selectable con- trol unit to make complex robot systems easier to operate. The robots are primarily used for obtaining information and manipulating dangerous objects or support emergency forces in dealing with crisis situations. Based on hazardous mission scenarios in which mobile robot systems are confronted with complex manipulation and maneuvering tasks (e.g., leakage of contaminants), new methods and concepts in the area of robot decision making, sensor data presentation and control concepts were developed to facilitate the handling and operation of assistance robots. The flexibility of the control concept approach is intended to increase the confidence of the emergency services and to provide intuitive operation of the assistance robots for every user. An intuitive control and stable communication for both control commands and feedback from the robot itself increase trust in the robotic system and its acceptance by the operators. These developments have been investigated in field trials with different types of robots and with network communication constraints.}, address = {Napoli, Italy}, author = {Edlinger, R. and Anschober, M. and Froschauer, R. and N{\"u}chter, A.}, booktitle = {31st IEEE International Conference on Robot and Human Interactive Communication (RO-MAN'22)}, keywords = {myown}, month = {August/September}, title = {{Modular HRI Approach with reliable and resilient wireless communication for rescue robots and first responders}}, year = 2022 }
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  Pose estimation and mapping based on IMU and LiDAR Kaltenthaler, J.; Lauterbach, H. A.; Borrmann, D.; Nüchter, A. in Proceedings of the 6th IFAC Symposium on Telematics Applications (TA ’22) (2022). 71–76.
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  In the field of autonomous motion and mapping, estimating the position and orientiation of a moving body is of high significance. This includes in particular the latest information about acceleration, speed, traveled distance and orientation. A wide range of different technologies exists that can be applied for this purpose. In case the state determination requires the use of inertial sensors only, it is well known that these types of sensors tend to drift with time. This leads to increasing errors in the calculated trajectory, which is unacceptable if precise position information is required such as for mapping. In this paper we present a method which significantly enhances the position estimation of inertial sensors by using a 2D light detection and ranging (LiDAR) sensor.

  @inproceedings{TA2022_2, abstract = {In the field of autonomous motion and mapping, estimating the position and orientiation of a moving body is of high significance. This includes in particular the latest information about acceleration, speed, traveled distance and orientation. A wide range of different technologies exists that can be applied for this purpose. In case the state determination requires the use of inertial sensors only, it is well known that these types of sensors tend to drift with time. This leads to increasing errors in the calculated trajectory, which is unacceptable if precise position information is required such as for mapping. In this paper we present a method which significantly enhances the position estimation of inertial sensors by using a 2D light detection and ranging (LiDAR) sensor.}, address = {Nancy, France}, author = {Kaltenthaler, J. and Lauterbach, H. A. and Borrmann, D. and N{\"u}chter, A.}, booktitle = {Proceedings of the 6th IFAC Symposium on Telematics Applications (TA '22)}, keywords = {imported}, month = {June}, pages = {71-76}, title = {{Pose estimation and mapping based on IMU and LiDAR}}, year = 2022 }
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  Radiance values inside lunar caves and lava tubes Rodeghiero, G.; Pernechele, C.; Munari, M.; Pozzobon, R.; Pajola, M.; Antonio, I. Di; Lucchetti, A.; Massironi, M.; Simioni, E.; Borrmann, D.; Maurelli, F.; Nüchter, A.; Rossi, A. P. in Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave, L. E. Coyle, S. Matsuura, M. D. Perrin (eds.) (2022). (Vol. 12180) 121803B.
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  here is currently a growing interest for the in-situ robotic and human exploration of the Moon’s surface and subsurface. In particular, several mission concepts foresee the exploration of lunar caves and underground structures like e.g. the lava tubes, (i.e. conduit formed by flowing lava from a volcanic vent that moves beneath the hardened surface of a lava flow) and other depressed morphologies such as permanently shadowed craters which could present in situ resources such as water ice. Given the limited onboard resources of these missions and extreme illumination conditions ranging from sunlight to complete darkness, the cameras might be capable of operating without the support of any artificial illumination system. This paper studies the radiance properties of a set of different lunar cave pits as illuminated uniquely by the sunlight for different Sun elevations above the Moon horizon and permanently shadowed craters such as Shackleton’s interior. This is as an endmember for complete darkness of extreme importance because it could be a cold trap for volatiles and a potential future human exploration target. The simulations are carried out using the OpticStudio ray tracing software and a Lambertian scattering model of the cave pit walls. The radiance maps within the caves can be used by the scientific community to estimate the typical Signal to Noise Ratio (SNR) of the required observations with optical cameras deployed on the lunar surface. This is accomplished both for directly illuminated, penumbra and umbra regions of the cave pit. We believe that the proposed investigations are of wide interest for the future missions to the Moon and its robotic and manned exploration.

  @inproceedings{SPIE_2022, abstract = {here is currently a growing interest for the in-situ robotic and human exploration of the Moon’s surface and subsurface. In particular, several mission concepts foresee the exploration of lunar caves and underground structures like e.g. the lava tubes, (i.e. conduit formed by flowing lava from a volcanic vent that moves beneath the hardened surface of a lava flow) and other depressed morphologies such as permanently shadowed craters which could present in situ resources such as water ice. Given the limited onboard resources of these missions and extreme illumination conditions ranging from sunlight to complete darkness, the cameras might be capable of operating without the support of any artificial illumination system. This paper studies the radiance properties of a set of different lunar cave pits as illuminated uniquely by the sunlight for different Sun elevations above the Moon horizon and permanently shadowed craters such as Shackleton’s interior. This is as an endmember for complete darkness of extreme importance because it could be a cold trap for volatiles and a potential future human exploration target. The simulations are carried out using the OpticStudio ray tracing software and a Lambertian scattering model of the cave pit walls. The radiance maps within the caves can be used by the scientific community to estimate the typical Signal to Noise Ratio (SNR) of the required observations with optical cameras deployed on the lunar surface. This is accomplished both for directly illuminated, penumbra and umbra regions of the cave pit. We believe that the proposed investigations are of wide interest for the future missions to the Moon and its robotic and manned exploration.}, author = {Rodeghiero, G. and Pernechele, C. and Munari, M. and Pozzobon, R. and Pajola, M. and Antonio, I. Di and Lucchetti, A. and Massironi, M. and Simioni, E. and Borrmann, D. and Maurelli, F. and N{\"u}chter, A. and Rossi, A. P.}, booktitle = {Space Telescopes and Instrumentation 2022: Optical, Infrared, and Millimeter Wave}, editor = {Coyle, Laura E. and Matsuura, Shuji and Perrin, Marshall D.}, keywords = {myown}, organization = {International Society for Optics and Photonics}, pages = {121803B}, publisher = {SPIE}, title = {{Radiance values inside lunar caves and lava tubes}}, volume = 12180, year = 2022 }
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  Sensor fusion of IMU and GPS for geofencing on an industrial control system for safe mowing in road areas Dumberger, S.; Edlinger, R.; Bauer, P.; Zauner, M.; Nüchter, A. in Proceedings of the Autrian Robotics Workshop (ARW ’22), M. Brandstötter, G. Steinbauer-Wagner, J. Piater, and L.-M. Faller (eds.) (2022). 91–96.
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  The paper presents the implementation of geofenc- ing on a mobile industrial controller for the automation of a mobile carrier vehicle for agricultural use. This system is used to prevent collision with well-known obstacles as well as avoid the accidental run-away of the vehicle under autonomous operation. It describes the mathematical principle used, as well as the additional features needed for a practical implementation on an industrial controller. As it is necessary to ensure the operation under real-world conditions, the paper also handles the data acquisition, pre-filtering and sensor fusion for system. Finally the correct behavior of the system is evaluated with multiple test-cases as well as experimental field tests.

  @inproceedings{ARW2022_2, abstract = {The paper presents the implementation of geofenc- ing on a mobile industrial controller for the automation of a mobile carrier vehicle for agricultural use. This system is used to prevent collision with well-known obstacles as well as avoid the accidental run-away of the vehicle under autonomous operation. It describes the mathematical principle used, as well as the additional features needed for a practical implementation on an industrial controller. As it is necessary to ensure the operation under real-world conditions, the paper also handles the data acquisition, pre-filtering and sensor fusion for system. Finally the correct behavior of the system is evaluated with multiple test-cases as well as experimental field tests.}, address = {Villach, Austria}, author = {Dumberger, S. and Edlinger, R. and Bauer, P. and Zauner, M. and N{\"u}chter, A.}, booktitle = {Proceedings of the Autrian Robotics Workshop (ARW '22)}, editor = {Brandst{\"o}tter, M. and Steinbauer-Wagner, G. and Piater, J. and and L.-M. Faller}, keywords = {imported}, month = {June}, pages = {91–96}, title = {Sensor fusion of IMU and GPS for geofencing on an industrial control system for safe mowing in road areas}, year = 2022 }
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  Solving Disaster-response Tasks at a Nuclear Power Plant under Realistic Conditions Edlinger, R.; Dumberger, S.; Föls, C.; Zouhar, D.; Nüchter, A. in Proceedings of the IEEE International Conference on Autonomous Robot Systems and Competitions (ICARSC ’22) (2022). 104–109.
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  Environmental disasters usually trigger devastating damage and, in the worst case, can also cause reactor accidents in nuclear power plants, see Fukushima disaster or other detailed analysis and reports of accident's causes. The correct assessment of natural disasters and the resulting combination with radiological and nuclear accidents, is a major challenge for rescue teams. The conditions under which rescue and recovery operations, as well as exploration and transport tasks, take place are often challenging for emergency responders and involve a certain potential for danger. Serious incidents in the last decades have shown that rescue teams have an urgent need of robotic platforms for fast exploration and scene understanding, especially in scenarios involving radiation. This paper describes the rescue robotic systems used in a test scenario of a nuclear power plant in which the robots must handle sources with real radiation and lessons learned from various application-specific tasks at the EnRicH competition.

  @inproceedings{ICARSC2022_1, abstract = {Environmental disasters usually trigger devastating damage and, in the worst case, can also cause reactor accidents in nuclear power plants, see Fukushima disaster or other detailed analysis and reports of accident's causes. The correct assessment of natural disasters and the resulting combination with radiological and nuclear accidents, is a major challenge for rescue teams. The conditions under which rescue and recovery operations, as well as exploration and transport tasks, take place are often challenging for emergency responders and involve a certain potential for danger. Serious incidents in the last decades have shown that rescue teams have an urgent need of robotic platforms for fast exploration and scene understanding, especially in scenarios involving radiation. This paper describes the rescue robotic systems used in a test scenario of a nuclear power plant in which the robots must handle sources with real radiation and lessons learned from various application-specific tasks at the EnRicH competition.}, address = {Santa Maria da Feira, Portugal}, author = {Edlinger, R. and Dumberger, S. and F{\"o}ls, C. and Zouhar, D. and N{\"u}chter, A.}, booktitle = {Proceedings of the IEEE International Conference on Autonomous Robot Systems and Competitions (ICARSC '22)}, keywords = {myown}, month = {April}, pages = {104–109}, title = {{Solving Disaster-response Tasks at a Nuclear Power Plant under Realistic Conditions}}, year = 2022 }
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  Synergetic use of Sentinel-1 and Sentinel-2 data for large-scale Land Use/Land Cover Mapping Brandmeier, M.; Hell, M.; Cherif, E.; Nüchter, A. in Proceedings of the EGU General Assembly 2022, Poster: Novel Methods and Applications of Satellite and Aerial Imagery (2022).
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  @inproceedings{EGU2022, address = {Vienna, Austria \& Online}, author = {Brandmeier, M. and Hell, M. and Cherif, E. and N{\"u}chter, A.}, booktitle = {Proceedings of the EGU General Assembly 2022, Poster: Novel Methods and Applications of Satellite and Aerial Imagery}, keywords = {myown}, month = {April}, number = {EGU2022-4300}, title = {{Synergetic use of Sentinel-1 and Sentinel-2 data for large-scale Land Use/Land Cover Mapping}}, year = 2022 }
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  Terrain prediction with a low-cost LIDAR sensor for mobile robots Edlinger, R.; Nüchter, A. in Proceedings of LowCost3D 2022, ISPRS Int. Archives Photogrammetry and Remote Sensing, Spatial Inf. Sci., XLVIII-2/W1-2022 (2022). 81–86.
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  Terrain modelling influences various aspects of mobile robot navigation. The ability to explore in rough terrain and to recognise ground conditions are essential to perform different activities efficiently, safely and satisfactorily. For this reason, intelligent vehicles and robotic systems need cognitive capabilities to understand the terrain and derive information from it. The information is mostly acquired and processed by very high resolution 3D-cameras and LiDAR sensors which provide full 360-degree environmental view to deliver accurate 3D data. The aim of this paper is to find out whether a low-cost sensor variant can measure sufficient and significant data from the terrain in order to modify the navigation behaviour and provide the correct control commands. In this paper we describe a low-cost sensor with Infrared Time-of-Flight (ToF) technology and 64 pixel depth image. Furthermore, different experiments on the detection of the sensor were conducted and with appropriate filters and signal processing algorithms the environmental perception could be significantly improved. In summary, our results provide both evidence and guidelines for the use of the selected sensor in environmental perception to improve local obstacle detection and terrain modelling, which we believe will lead to a very cost-effective improvement in competence and situational awareness.

  @inproceedings{LC2022, abstract = {Terrain modelling influences various aspects of mobile robot navigation. The ability to explore in rough terrain and to recognise ground conditions are essential to perform different activities efficiently, safely and satisfactorily. For this reason, intelligent vehicles and robotic systems need cognitive capabilities to understand the terrain and derive information from it. The information is mostly acquired and processed by very high resolution 3D-cameras and LiDAR sensors which provide full 360-degree environmental view to deliver accurate 3D data. The aim of this paper is to find out whether a low-cost sensor variant can measure sufficient and significant data from the terrain in order to modify the navigation behaviour and provide the correct control commands. In this paper we describe a low-cost sensor with Infrared Time-of-Flight (ToF) technology and 64 pixel depth image. Furthermore, different experiments on the detection of the sensor were conducted and with appropriate filters and signal processing algorithms the environmental perception could be significantly improved. In summary, our results provide both evidence and guidelines for the use of the selected sensor in environmental perception to improve local obstacle detection and terrain modelling, which we believe will lead to a very cost-effective improvement in competence and situational awareness.}, address = {W{\"u}rzburg, Germany}, author = {Edlinger, R. and N{\"u}chter, A.}, booktitle = {Proceedings of LowCost3D 2022}, keywords = {imported}, month = {December}, pages = {81–86}, series = {ISPRS Int. Archives Photogrammetry and Remote Sensing, Spatial Inf. Sci., XLVIII-2/W1-2022}, title = {{T}errain prediction with a low-cost {LIDAR} sensor for mobile robots}, year = 2022 }
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  Testing AGV mobility control method for MANET coverage optimization using procedural simulation Sauer, C.; Lyczkowski, E.; Schmidt, M.; Nüchter, A.; Hoßfeld, T. in Computer Communications (2022). 194 189–201.
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  In industrial applications continuous wireless connectivity of mobile clients can rarely by guaranteed. Lack of communication negatively impacts the performance of industrial automation systems, e.g. Automated Guided Vehicle (AGV) fleets. Utilizing industrial Mobile Ad-hoc NETworks (MANETs) and an adaptive positioning scheme can reduce the number of disconnections in AGV fleets. Therefore, the performance of the mobile system (e.g. AGV fleet) is improved and factory efficiency increased. In this work procedural simulation is used to examine wireless communication in industrial applications. This method enables the observation of the interaction of mobility control system, network status and robotic system performance independently from a specific environment or scenario. Novel insights on the effectiveness of ad-hoc communication in industrial applications and the correlation of AGV fleet connectedness and AGV fleet transport performance are presented. Additionally, a control method is proposed, which improves the network coverage of an industrial MANET and efficiency of AGV fleets.

  @article{SAUER2022189, abstract = {In industrial applications continuous wireless connectivity of mobile clients can rarely by guaranteed. Lack of communication negatively impacts the performance of industrial automation systems, e.g. Automated Guided Vehicle (AGV) fleets. Utilizing industrial Mobile Ad-hoc NETworks (MANETs) and an adaptive positioning scheme can reduce the number of disconnections in AGV fleets. Therefore, the performance of the mobile system (e.g. AGV fleet) is improved and factory efficiency increased. In this work procedural simulation is used to examine wireless communication in industrial applications. This method enables the observation of the interaction of mobility control system, network status and robotic system performance independently from a specific environment or scenario. Novel insights on the effectiveness of ad-hoc communication in industrial applications and the correlation of AGV fleet connectedness and AGV fleet transport performance are presented. Additionally, a control method is proposed, which improves the network coverage of an industrial MANET and efficiency of AGV fleets.}, author = {Sauer, C. and Lyczkowski, E. and Schmidt, M. and N{\"u}chter, A. and Ho{\ss}feld, T.}, journal = {Computer Communications}, keywords = {imported}, pages = {189–201}, title = {Testing AGV mobility control method for MANET coverage optimization using procedural simulation}, volume = 194, year = 2022 }
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  The concept of a maximal network plan to enhance automated decision making in production steering Larek, R.; Wagner, J. C.; Grendel, H.; Nüchter, A. in Production Engineering (2022).
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  Digitalization is a major driver of competitiveness in industry. Especially, automated scheduling systems are broadly available to deal with production steering in complex production systems. Their underlying concept is the network plan to describe the logical relation between different production steps for the completion of a production process. The network plan, however, is limited to contain only one standard process and allows therefore basically only the automated variation of execution time of each step within the given logical sequence. This is sufficient as long as the production process and the boundary conditions, such as resource availability, are stable to a certain degree. This work introduces an enhancement of the concept of the network plan, the Maximal Network Plan, that is designed to automatically cope with disruptions. It stores additional alternative sequences, weighted according to their priority in comparison to the standard process. Therefore, a numerical decision making is possible in terms of also varying the order of production tasks to achieve a maximum performance for the overall process. Instead of waiting for a disruption in the standard process to be solved, an alternative sequence will be proposed to increase overall progress by circumventing the blocked step. This concept has been developed and tested for complex assembly tasks, such as the production of air- and spacecraft structures and systems. In conjunction with the use of mobile computing devices instead of paper-based work order documents it allows a very fast and dynamic production steering, also in the case of substantial disruptions in the standard process.

  @article{ProdEng_2022, abstract = {Digitalization is a major driver of competitiveness in industry. Especially, automated scheduling systems are broadly available to deal with production steering in complex production systems. Their underlying concept is the network plan to describe the logical relation between different production steps for the completion of a production process. The network plan, however, is limited to contain only one standard process and allows therefore basically only the automated variation of execution time of each step within the given logical sequence. This is sufficient as long as the production process and the boundary conditions, such as resource availability, are stable to a certain degree. This work introduces an enhancement of the concept of the network plan, the Maximal Network Plan, that is designed to automatically cope with disruptions. It stores additional alternative sequences, weighted according to their priority in comparison to the standard process. Therefore, a numerical decision making is possible in terms of also varying the order of production tasks to achieve a maximum performance for the overall process. Instead of waiting for a disruption in the standard process to be solved, an alternative sequence will be proposed to increase overall progress by circumventing the blocked step. This concept has been developed and tested for complex assembly tasks, such as the production of air- and spacecraft structures and systems. In conjunction with the use of mobile computing devices instead of paper-based work order documents it allows a very fast and dynamic production steering, also in the case of substantial disruptions in the standard process.}, author = {Larek, R. and Wagner, J. C. and Grendel, H. and N{\"u}chter, A.}, journal = {Production Engineering}, keywords = {imported}, month = {July}, title = {The concept of a maximal network plan to enhance automated decision making in production steering}, year = 2022 }
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  The concept of rod-driven locomotion for spherical lunar exploration robots Zevering, J.; Borrmann, D.; Bredenbeck, A.; Nüchter, A. in IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS ’22) (2022). 5656–5663.
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  A spherical robotic probe has several advantages in rough environments and has therefore raised interest for application in planetary exploration. A sphere is well-suited to protect high-sensitive payloads, however, the locomotion system for planetary surfaces raises several challenges. This paper presents a novel locomotion system consisting of linear actuators which are usable in a multi-functional fashion. Apart from pushing and bringing leverage for locomotion the extendable rods enable a tripod mode for improved sensing. The developed solutions offer a mathematical-physical system description, simple algorithms for the control of locomotion and balancing as well as general calculations for determining the maximum achievable performance parameters of such a robot. The first built prototype shows the basic suitability of the system and reveals directions for further research.

  @inproceedings{IROS2022_1, abstract = {A spherical robotic probe has several advantages in rough environments and has therefore raised interest for application in planetary exploration. A sphere is well-suited to protect high-sensitive payloads, however, the locomotion system for planetary surfaces raises several challenges. This paper presents a novel locomotion system consisting of linear actuators which are usable in a multi-functional fashion. Apart from pushing and bringing leverage for locomotion the extendable rods enable a tripod mode for improved sensing. The developed solutions offer a mathematical-physical system description, simple algorithms for the control of locomotion and balancing as well as general calculations for determining the maximum achievable performance parameters of such a robot. The first built prototype shows the basic suitability of the system and reveals directions for further research.}, address = {Kyoto, Japan}, author = {Zevering, J. and Borrmann, D. and Bredenbeck, A. and N{\"u}chter, A.}, booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS '22)}, keywords = {myown}, month = {October}, pages = {5656–5663}, title = {{The concept of rod-driven locomotion for spherical lunar exploration robots}}, year = 2022 }
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  Trajectory Optimization and Following for a Three Degrees of Freedom Overactuated Floating Platform Bredenbeck, A.; Vyas, S.; Zwick, M.; Borrmann, D.; Olivares-Mendez, M.A.; Nüchter, A. in IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS ’22) (2022). 4084–4091.
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  Applications of space robotics, such as Active Space Debris Removal (ASDR), require representative test- ing before launch. A commonly used approach to emulate the microgravity environment in space are air-bearing based platforms on flat-floors, such as the European Space Agency’s Orbital Robotics and GNC Lab (ORGL). This work proposes a control architecture for a floating platform at the ORGL, equipped with eight solenoid-valve-based thrusters and one reaction wheel. The control architecture consists of two main components: a trajectory planner that finds optimal trajectories connecting two states and a trajectory follower that follows any physically feasible trajectory. The controller is first evaluated within an introduced simulation, achieving a 100\% success rate at finding and following trajectories to the origin within a Monte-Carlo test. Individual trajectories are also successfully followed by the physical system. In this work, we showcase the ability of the controller to reject disturbances and follow a straight-line trajectory within tens of centimeters.

  @inproceedings{IROS2022_2, abstract = {Applications of space robotics, such as Active Space Debris Removal (ASDR), require representative test- ing before launch. A commonly used approach to emulate the microgravity environment in space are air-bearing based platforms on flat-floors, such as the European Space Agency’s Orbital Robotics and GNC Lab (ORGL). This work proposes a control architecture for a floating platform at the ORGL, equipped with eight solenoid-valve-based thrusters and one reaction wheel. The control architecture consists of two main components: a trajectory planner that finds optimal trajectories connecting two states and a trajectory follower that follows any physically feasible trajectory. The controller is first evaluated within an introduced simulation, achieving a 100\% success rate at finding and following trajectories to the origin within a Monte-Carlo test. Individual trajectories are also successfully followed by the physical system. In this work, we showcase the ability of the controller to reject disturbances and follow a straight-line trajectory within tens of centimeters.}, address = {Kyoto, Japan}, author = {Bredenbeck, A. and Vyas, S. and Zwick, M. and Borrmann, D. and Olivares-Mendez, M.A. and N{\"u}chter, A.}, booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS '22)}, keywords = {myown}, month = {October}, pages = {4084–4091}, title = {{Trajectory Optimization and Following for a Three Degrees of Freedom Overactuated Floating Platform}}, year = 2022 }
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  Unconventional Trajectories for Mobile 3D Scanning and Mapping Arzberger, F.; Zevering, J.; Bredenbeck, A.; Borrmann, D.; Nüchter, A. in Autonomous Mobile Mapping Robots, J. B\ce}}dkowski (ed.) (2022).
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  State-of-the-art LiDAR-based 3D scanning and mapping systems focus on scenarios where good sensing coverage is ensured, such as drones, wheeled robots, cars, or backpack-mounted systems. However, in some scenarios more unconventional sensor trajectories come naturally, e.g., rolling, descending, or oscillating back and forth, but the literature on these is relatively sparse. As a result, most implementations developed in the past are not able to solve the SLAM problem in such conditions. In this chapter, we propose a robust offline-batch SLAM system that is able to address more challenging trajectories, which are characterized by weak angles of incidence and limited FOV while scanning. The proposed SLAM system is an upgraded version of our previous work and takes as input the raw points and prior pose estimates, yet the latter are subject to large amounts of drift. Our approach is a two-staged algorithm where in the first stage coarse alignment is fast achieved by matching planar polygons. In the second stage, we utilize a graph-based SLAM algorithm for further refinement. We evaluate the mapping accu- racy of the algorithm on our own recorded datasets using high-resolution ground truth maps, which are available from a TLS.

  @incollection{INTECH22A, abstract = {State-of-the-art LiDAR-based 3D scanning and mapping systems focus on scenarios where good sensing coverage is ensured, such as drones, wheeled robots, cars, or backpack-mounted systems. However, in some scenarios more unconventional sensor trajectories come naturally, e.g., rolling, descending, or oscillating back and forth, but the literature on these is relatively sparse. As a result, most implementations developed in the past are not able to solve the SLAM problem in such conditions. In this chapter, we propose a robust offline-batch SLAM system that is able to address more challenging trajectories, which are characterized by weak angles of incidence and limited FOV while scanning. The proposed SLAM system is an upgraded version of our previous work and takes as input the raw points and prior pose estimates, yet the latter are subject to large amounts of drift. Our approach is a two-staged algorithm where in the first stage coarse alignment is fast achieved by matching planar polygons. In the second stage, we utilize a graph-based SLAM algorithm for further refinement. We evaluate the mapping accu- racy of the algorithm on our own recorded datasets using high-resolution ground truth maps, which are available from a TLS.}, address = {Rijeka, Croatia}, author = {Arzberger, F. and Zevering, J. and Bredenbeck, A. and Borrmann, D. and N{\"u}chter, A.}, booktitle = {{A}utonomous {M}obile {M}apping {R}obots}, chapter = 9, editor = {B{\c{e}}dkowski, J.}, keywords = {imported}, publisher = {IntechOpen}, title = {{U}nconventional {T}rajectories for {M}obile {3D} {S}canning and {M}apping}, year = 2022 }
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  Visuelle Odometrie und SLAM für die Bewegungs-kompensation und mobile Kartierung mit einem optischen 3D-Unterwassersensor Bleier, M.; Munkelt, C.; Heinze, M.; Bräuer-Burchardt, C.; Lauterbach, H. A.; van der Lucht, J.; Nüchter, A. in Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beiträge der Oldenburger 3D-Tage 2022, Jade Hochschule (2022). 394–405.
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  Im Projekt UWSensor wurde ein neuartiger optischer 3D-Unterwassersensor basierend auf Streifenlichtprojektion mit einem GOBO-Projektor entwickelt. Das Sensorsystem ermöglicht eine flächige 3D-Erfassung mit hoher Genauigkeit und Abtastrate, sowie eine gleichzeitige Erfassung von Farbdaten. Dies erlaubt den Einsatz zur mobilen Kartierung und 3D-Erfassung mit einem Unterwasserfahrzeug. Dieser Beitrag beschäftigt sich mit der Bewegungsschätzung sowie der Fusion der Einzelscans in ein global konsistentes 3D-Modell. Hierbei wird zunächst visuelle Odometrie in Kombination mit einem faseroptischen Gyroskop genutzt, um die Eigenbewegung des Sensors zu schätzen. Die daraus latenzarm abgeleiteten Posen werden dem Live-Aufnahmesystem des Sensors bereitgestellt, um eine online-Bewegungskompensation der den 3D Scans zugrundeliegenden Serie von Kamerabildern zu realisieren. Anschließend wird eine mehrstufigen Registrierungsstrategie angewendet, um die Schätzung der Trajektorie weiter zu verfeinern. Zunächst wird mittels des Iterative Closest Point (ICP) Algorithmus jede 3D-Punktwolke sequentiell gegen ihre Vorgänger registriert. Da sich kleine Restfehler in der Registrierung akkumulieren, erfolgt im nächsten Schritt eine zweite Registrierung mittels eines zeitkontinuierlichen ICP-Verfahren. Hierbei werden mehrere Punktwolken zu Teilkarten zusammengefasst und gegeneinander registriert, wobei die Verbesserungen der Trajektorie im Anschluss wiederum auf die einzelnen Posen der Punktwolken verteilt werden, um die Kontinuität der Trajektorie zu bewahren. In diesem Registrierungsschritt werden auch Schleifen in der Trajektorie erkannt und geschlossen, um den Drift zu korrigieren. Für die Kalibrierung des Sensorsystems wurde eine Kombination von Aufnahmen in Luft und im Wasser eingesetzt. Das Verfahren wurde auf dynamischen Aufnahmen mit dem neuentwickelten Sensorsystem in einem Wasserbecken getestet und evaluiert. Hierbei wurden sowohl bekannte Testkörper mit bewegtem Sensor im Wasser eingescannt, als auch die berechneten Trajektorien anhand der Bewegungsdaten des Portalsystems validiert.

  @inproceedings{3DTAGE2022_2, abstract = {Im Projekt UWSensor wurde ein neuartiger optischer 3D-Unterwassersensor basierend auf Streifenlichtprojektion mit einem GOBO-Projektor entwickelt. Das Sensorsystem ermöglicht eine flächige 3D-Erfassung mit hoher Genauigkeit und Abtastrate, sowie eine gleichzeitige Erfassung von Farbdaten. Dies erlaubt den Einsatz zur mobilen Kartierung und 3D-Erfassung mit einem Unterwasserfahrzeug. Dieser Beitrag beschäftigt sich mit der Bewegungsschätzung sowie der Fusion der Einzelscans in ein global konsistentes 3D-Modell. Hierbei wird zunächst visuelle Odometrie in Kombination mit einem faseroptischen Gyroskop genutzt, um die Eigenbewegung des Sensors zu schätzen. Die daraus latenzarm abgeleiteten Posen werden dem Live-Aufnahmesystem des Sensors bereitgestellt, um eine online-Bewegungskompensation der den 3D Scans zugrundeliegenden Serie von Kamerabildern zu realisieren. Anschließend wird eine mehrstufigen Registrierungsstrategie angewendet, um die Schätzung der Trajektorie weiter zu verfeinern. Zunächst wird mittels des Iterative Closest Point (ICP) Algorithmus jede 3D-Punktwolke sequentiell gegen ihre Vorgänger registriert. Da sich kleine Restfehler in der Registrierung akkumulieren, erfolgt im nächsten Schritt eine zweite Registrierung mittels eines zeitkontinuierlichen ICP-Verfahren. Hierbei werden mehrere Punktwolken zu Teilkarten zusammengefasst und gegeneinander registriert, wobei die Verbesserungen der Trajektorie im Anschluss wiederum auf die einzelnen Posen der Punktwolken verteilt werden, um die Kontinuität der Trajektorie zu bewahren. In diesem Registrierungsschritt werden auch Schleifen in der Trajektorie erkannt und geschlossen, um den Drift zu korrigieren. Für die Kalibrierung des Sensorsystems wurde eine Kombination von Aufnahmen in Luft und im Wasser eingesetzt. Das Verfahren wurde auf dynamischen Aufnahmen mit dem neuentwickelten Sensorsystem in einem Wasserbecken getestet und evaluiert. Hierbei wurden sowohl bekannte Testkörper mit bewegtem Sensor im Wasser eingescannt, als auch die berechneten Trajektorien anhand der Bewegungsdaten des Portalsystems validiert.}, author = {Bleier, M. and Munkelt, C. and Heinze, M. and Br{\"a}uer-Burchardt, C. and Lauterbach, H. A. and van der Lucht, J. and N{\"u}chter, A.}, booktitle = {Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beitr{\"a}ge der Oldenburger 3D-Tage 2022, Jade Hochschule}, keywords = {myown}, month = {February}, pages = {394–405}, publisher = {Wichmann}, title = {{Visuelle Odometrie und SLAM für die Bewegungs-kompensation und mobile Kartierung mit einem optischen 3D-Unterwassersensor}}, year = 2022 }
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  WIP: Real-world 3D models derived from mobile mapping for ray launching based propagation loss modeling Wahl, T.; Borrmann, D.; Bleier, M.; Nüchter, A.; Wiemann, T.; Hänel, T.; Aschenbruck, N. in Proceedings of the 23rd IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM ’22) (2022). 1–4.
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  This work in progress paper presents an automated approach for network coverage prediction in real-world environments by combining mobile mapping, 3D mesh generation, and a ray launching based network simulator. We identify the challenges and demonstrate the functionality of such a pipeline. We preview an empirical evaluation in a realistic real-world environment.

  @inproceedings{WOWMOM2022, abstract = {This work in progress paper presents an automated approach for network coverage prediction in real-world environments by combining mobile mapping, 3D mesh generation, and a ray launching based network simulator. We identify the challenges and demonstrate the functionality of such a pipeline. We preview an empirical evaluation in a realistic real-world environment.}, address = {Belfast, UK}, author = {Wahl, T. and Borrmann, D. and Bleier, M. and {N{\"u}chter}, A. and Wiemann, T. and H{\"a}nel, T. and Aschenbruck, N.}, booktitle = {Proceedings of the 23rd IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM '22)}, keywords = {imported}, month = {June}, pages = {1–4}, title = {{WIP: Real-world 3D models derived from mobile mapping for ray launching based propagation loss modeling}}, year = 2022 }

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  CALIBRATION AND VALIDATION OF THE INTEL T265 FOR VISUAL LOCALISATION AND TRACKING UNDERWATER Appelt, T.; van der Lucht, J.; Bleier, M.; Nüchter, A. in Proceedings of the ISPRS Congress 2021, The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (2021). 635–641.
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  Localization and navigation for autonomous underwater vehicle (AUV) has always been a major challenge and many situations complex solutions had to be devised. One of the main approaches is visual odometry using a stereo camera. In this study, the Intel T265 fisheye stereo camera has been calibrated and tested to determine it’s usability for localisation and navigation under water as an alternative to more complex systems. Firstly the Intel T265 fisheye stereo camera was appropriately calibrated inside a water filled container. This calibration consisting of camera and distortion parameters got programmed onto the T265 fisheye stereo camera to take the differences between land and underwater usage into account. Successive the calibration, the accuracy and the precision of the T265 fisheye stereo camera were tested using a linear, a circular and finally a chaotic motion. This includes a review of the localisation and tracking of the cameras visual odometry compared to a ground truth provided by an OptiTrack V120:Trio to account for scaling, accuracy and precision. Also experiments to determine the usability with fast chaotic motions were performed and analysed. Finally, a conclusion concerning the applicability of the Intel T265 fisheye stereo camera, the challenges using this model, the possibilities for low cost operations and the main challenges for future work is conducted.

  @inproceedings{ISPRSCongress2021a, abstract = {Localization and navigation for autonomous underwater vehicle (AUV) has always been a major challenge and many situations complex solutions had to be devised. One of the main approaches is visual odometry using a stereo camera. In this study, the Intel T265 fisheye stereo camera has been calibrated and tested to determine it’s usability for localisation and navigation under water as an alternative to more complex systems. Firstly the Intel T265 fisheye stereo camera was appropriately calibrated inside a water filled container. This calibration consisting of camera and distortion parameters got programmed onto the T265 fisheye stereo camera to take the differences between land and underwater usage into account. Successive the calibration, the accuracy and the precision of the T265 fisheye stereo camera were tested using a linear, a circular and finally a chaotic motion. This includes a review of the localisation and tracking of the cameras visual odometry compared to a ground truth provided by an OptiTrack V120:Trio to account for scaling, accuracy and precision. Also experiments to determine the usability with fast chaotic motions were performed and analysed. Finally, a conclusion concerning the applicability of the Intel T265 fisheye stereo camera, the challenges using this model, the possibilities for low cost operations and the main challenges for future work is conducted.}, address = {Nice, France}, author = {Appelt, T. and van der Lucht, J. and Bleier, M. and N{\"u}chter, A.}, booktitle = {Proceedings of the ISPRS Congress 2021}, keywords = {imported}, number = {XLIII-B2-2021}, pages = {635–641}, series = {The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences}, title = {CALIBRATION AND VALIDATION OF THE INTEL T265 FOR VISUAL LOCALISATION AND TRACKING UNDERWATER}, year = 2021 }
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  Combining LiDAR Scan Matching with Stereo Visual Odometry Using Curvefusion Du, S.; Li, X.; Lauterbach, H. A.; Borrmann, D.; Nüchter, A. in Proceedings of the IEEE International Conference on Computer, Control and Robotics (ICCCR ’21) (2021). 335–339.
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  In this paper, we present a novel algorithm, namely Curvefusion for integrating LiDAR scan matching with stereo visual odometry. First, 6-DOF pose trajectories are estimated by utilizing SOFT odometry, which is the state of the art stereo visual odometry based on feature selection and tracking, and the well-known ICP scan matching algorithm, respectively. Second, a deformation-based multi-sensor fusion method, namely curvefusion is applied. The proposed fusion method does not rely on a sensor model. As long as the trajectories of the sensors to be fused are given, we can obtain an optimized fusion trajectory, which greatly improves the computational efficiency. Experiments based on publicly available KITTI data set show that the proposed method outperforms or achieves similar performance compared with the state-of-the-art odometry methods.

  @inproceedings{ICCCR2021, abstract = {In this paper, we present a novel algorithm, namely Curvefusion for integrating LiDAR scan matching with stereo visual odometry. First, 6-DOF pose trajectories are estimated by utilizing SOFT odometry, which is the state of the art stereo visual odometry based on feature selection and tracking, and the well-known ICP scan matching algorithm, respectively. Second, a deformation-based multi-sensor fusion method, namely curvefusion is applied. The proposed fusion method does not rely on a sensor model. As long as the trajectories of the sensors to be fused are given, we can obtain an optimized fusion trajectory, which greatly improves the computational efficiency. Experiments based on publicly available KITTI data set show that the proposed method outperforms or achieves similar performance compared with the state-of-the-art odometry methods.}, author = {{Du}, S. and {Li}, X. and {Lauterbach}, H. A. and {Borrmann}, D. and {N{\"u}chter}, A.}, booktitle = {Proceedings of the IEEE International Conference on Computer, Control and Robotics (ICCCR '21)}, keywords = {myown}, pages = {335–339}, title = {Combining LiDAR Scan Matching with Stereo Visual Odometry Using Curvefusion}, year = 2021 }
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  DAEDALUS -- Descent And Exploration in Deep Autonomy of Lava Underground Structures Rossi, A. P.; Maurelli, F.; Unnithan, V.; Dreger, H.; Mathewos, K.; Pradhan, N.; Corbeanu, D.-A.; Pozzobon, R.; Massironi, M.; Ferrari, S.; Pernechele, C.; Paoletti, L.; Simioni, E.; Pajola, M.; Santagata, T.; Borrmann, D.; Nüchter, A.; Bredenbeck, A.; Zevering, J.; Arzberger, F.; Mantilla, C. A. R. in Uni Wuerzburg Research Notes in Robotics and Telematics (2021). 1–190. Julius Maximilian University of Würzburg.
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  The DAEDALUS mission concept aims at exploring and characterising the entrance and initial part of Lunar lava tubes within a compact, tightly integrated spherical robotic device, with a complementary payload set and autonomous capabilities. The mission concept addresses specifically the identification and characterisation of potential resources for future ESA exploration, the local environment of the subsurface and its geologic and compositional structure. A sphere is ideally suited to protect sensors and scientific equipment in rough, uneven environments. It will house laser scanners, cameras and ancillary payloads. The sphere will be lowered into the skylight and will explore the entrance shaft, associated caverns and conduits. Lidar (light detection and ranging) systems produce 3D models with high spatial accuracy independent of lighting conditions and visible features. Hence this will be the primary exploration toolset within the sphere. The additional payload that can be accommodated in the robotic sphere consists of camera systems with panoramic lenses and scanners such as multi-wavelength or single-photon scanners. A moving mass will trigger movements. The tether for lowering the sphere will be used for data communication and powering the equipment during the descending phase. Furthermore, the connector tether-sphere will host a WIFI access point, such that data of the conduit can be transferred to the surface relay station. During the exploration phase, the robot will be disconnected from the cable, and will use wireless communication. Emergency autonomy software will ensure that in case of loss of communication, the robot will continue the nominal mission.

  @book{DAEDALUS2021, abstract = {The DAEDALUS mission concept aims at exploring and characterising the entrance and initial part of Lunar lava tubes within a compact, tightly integrated spherical robotic device, with a complementary payload set and autonomous capabilities. The mission concept addresses specifically the identification and characterisation of potential resources for future ESA exploration, the local environment of the subsurface and its geologic and compositional structure. A sphere is ideally suited to protect sensors and scientific equipment in rough, uneven environments. It will house laser scanners, cameras and ancillary payloads. The sphere will be lowered into the skylight and will explore the entrance shaft, associated caverns and conduits. Lidar (light detection and ranging) systems produce 3D models with high spatial accuracy independent of lighting conditions and visible features. Hence this will be the primary exploration toolset within the sphere. The additional payload that can be accommodated in the robotic sphere consists of camera systems with panoramic lenses and scanners such as multi-wavelength or single-photon scanners. A moving mass will trigger movements. The tether for lowering the sphere will be used for data communication and powering the equipment during the descending phase. Furthermore, the connector tether-sphere will host a WIFI access point, such that data of the conduit can be transferred to the surface relay station. During the exploration phase, the robot will be disconnected from the cable, and will use wireless communication. Emergency autonomy software will ensure that in case of loss of communication, the robot will continue the nominal mission.}, address = {Julius Maximilian University of W{\"u}rzburg}, author = {Rossi, A. P. and Maurelli, F. and Unnithan, V. and Dreger, H. and Mathewos, K. and Pradhan, N. and Corbeanu, D.-A. and Pozzobon, R. and Massironi, M. and Ferrari, S. and Pernechele, C. and Paoletti, L. and Simioni, E. and Pajola, M. and Santagata, T. and Borrmann, D. and N{\"u}chter, A. and Bredenbeck, A. and Zevering, J. and Arzberger, F. and Mantilla, C. A. R.}, keywords = {myown}, month = {March}, pages = {1–190}, series = {Uni Wuerzburg Research Notes in Robotics and Telematics}, title = {DAEDALUS – Descent And Exploration in Deep Autonomy of Lava Underground Structures}, year = 2021 }
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  IMU-based pose-estimation for spherical robots with limited resources Zevering, J.; Bredenbeck, A.; Arzberger, F.; Borrmann, D.; Nüchter, A. in Proceedings of the IEEE International Conference on Multisensor Fusion and Integration (MFI ’21) (2021).
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  @inproceedings{MFI2021, address = {Karlsruhe, Germany}, author = {Zevering, J. and Bredenbeck, A. and Arzberger, F. and Borrmann, D. and N{\"u}chter, A.}, booktitle = {Proceedings of the IEEE International Conference on Multisensor Fusion and Integration (MFI '21)}, keywords = {myown}, month = {September}, title = {IMU-based pose-estimation for spherical robots with limited resources}, year = 2021 }
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  Indoor 3D: Overview on Scanning and Reconstruction Methods Lehtola, V. V.; Nikoohemat, S.; Nüchter, A. in Handbook of Big Geospatial Data, M. Werner, Y.-Y. Chiang (eds.) (2021). 55–97.
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  This chapter covers the essentials regarding indoor 3D data, from scanning to reconstruction. It is aimed for education and professionals. The order of presentation is background, history in measurement method development, sensors, sensor systems, positioning algorithms, reconstruction, and applications. The authors' backgrounds are in indoor 3D, mobile laser scanning, indoor reconstruction, and robotics. In order to maintain a coherence in the text and provide some useful tools for the reader, we have selected to focus solely on the ICP version of simultaneous localization and mapping (SLAM). Regardless, this should give a solid base for the reader to understand other (e.g. probabilistic) indoor SLAM methods as well. Reconstruction algorithms (starting from room segmentation and opening detection) are discussed with the help of abundant figures. At the very end, we discuss future trends with a connection to the current applications and propose some exercise questions for students.

  @inbook{Lehtola2021, abstract = {This chapter covers the essentials regarding indoor 3D data, from scanning to reconstruction. It is aimed for education and professionals. The order of presentation is background, history in measurement method development, sensors, sensor systems, positioning algorithms, reconstruction, and applications. The authors' backgrounds are in indoor 3D, mobile laser scanning, indoor reconstruction, and robotics. In order to maintain a coherence in the text and provide some useful tools for the reader, we have selected to focus solely on the ICP version of simultaneous localization and mapping (SLAM). Regardless, this should give a solid base for the reader to understand other (e.g. probabilistic) indoor SLAM methods as well. Reconstruction algorithms (starting from room segmentation and opening detection) are discussed with the help of abundant figures. At the very end, we discuss future trends with a connection to the current applications and propose some exercise questions for students.}, address = {Cham}, author = {Lehtola, V. V. and Nikoohemat, S. and N{\"u}chter, A.}, booktitle = {Handbook of Big Geospatial Data}, editor = {Werner, Martin and Chiang, Yao-Yi}, keywords = {myown}, pages = {55–97}, publisher = {Springer International Publishing}, title = {Indoor 3D: Overview on Scanning and Reconstruction Methods}, year = 2021 }
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  L.U.N.A. - A Laser-Mapping Unidirectional Navigation Actuator Zevering, J.; Bredenbeck, A.; Arzberger, F.; Borrmann, D.; Nüchter, A. in Proceedings of the 17th International Symposium of Experimental Robotics (ISER ’20), Springer Proceedings in Advanced Robotics (2021). 85–94.
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  This paper proposes an autonomous approach to 3D mapping using the concept of impulse by conservation of angular momentum (IBCOAM) as a unidirectional drive to roll a 2D laser scanner in an IMU equipped, pose-tracked spherical robot system. An experimental prototype of the robot is introduced, giving details about the hardware. The laser scanning results as well as the IBCOAM drive data that have been gathered using the prototype are analyzed, revealing technical challenges.

  @inproceedings{ISER2021, abstract = {This paper proposes an autonomous approach to 3D mapping using the concept of impulse by conservation of angular momentum (IBCOAM) as a unidirectional drive to roll a 2D laser scanner in an IMU equipped, pose-tracked spherical robot system. An experimental prototype of the robot is introduced, giving details about the hardware. The laser scanning results as well as the IBCOAM drive data that have been gathered using the prototype are analyzed, revealing technical challenges.}, address = {Valetta, Malta}, author = {Zevering, J. and Bredenbeck, A. and Arzberger, F. and Borrmann, D. and N{\"u}chter, A.}, booktitle = {Proceedings of the 17th International Symposium of Experimental Robotics (ISER '20)}, keywords = {myown}, month = {March}, pages = {85–94}, series = {Springer Proceedings in Advanced Robotics}, title = {{{L.U.N.A.} - A Laser-Mapping Unidirectional Navigation Actuator}}, year = 2021 }
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  Lunar Caves Exploration with the DAEDALUS Spherical Robot Borrmann, D.; Nüchter, A.; Bredenbeck, A.; Zevering, J.; Arzberger, F.; Mantilla, C. A. Reyes; Rossi, A. P.; Maurelli, F.; Unnithan, V.; Dreger, H.; Mathewos, K.; Pradhan, N.; Pozzobon, R.; Massironi, M.; Ferrari, S.; Pernechele, C.; Paoletti, L.; Simioni, E.; Pajola, M.; Santagata, T. in Proceedings of the 52nd Lunar and Planetary Science Conference (LPSC ’21) (2021).
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  @inproceedings{LPSC2012_2, address = {virtual meeting}, author = {Borrmann, D. and N{\"u}chter, A. and Bredenbeck, A. and Zevering, J. and Arzberger, F. and Mantilla, C. A. Reyes and Rossi, A. P. and Maurelli, F. and Unnithan, V. and Dreger, H. and Mathewos, K. and Pradhan, N. and Pozzobon, R. and Massironi, M. and Ferrari, S. and Pernechele, C. and Paoletti, L. and Simioni, E. and Pajola, M. and Santagata, T.}, booktitle = {Proceedings of the 52nd Lunar and Planetary Science Conference (LPSC '21)}, keywords = {imported}, month = {March}, organization = {Universities Space Research Association, Lunar and Planetary Institute}, title = {Lunar Caves Exploration with the DAEDALUS Spherical Robot}, year = 2021 }
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  Marius Hills Skylight hazard characterization as a possible landing site for lunar subsurface exploration Pozzobon, R.; Rossi, A. P.; Ferrari, S.; Massironi, M.; Pajola, M.; Nüchter, A.; Borrmann, D.; Zevering, J.; Bredenbeck, A.; Arzberger, F.; Mantilla, C. A. Reyes; Maurelli, F.; Unnithan, V.; Dreger, H.; Mathewos, K.; Pradhan, N.; Pernechele, C.; Paoletti, L.; Simioni, E.; Santagata, T. in Proceedings of the 52nd Lunar and Planetary Science Conference (LPSC ’21) (2021).
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  @inproceedings{LPSC2012_1, address = {virtual meeting}, author = {Pozzobon, R. and Rossi, A. P. and Ferrari, S. and Massironi, M. and Pajola, M. and N{\"u}chter, A. and Borrmann, D. and Zevering, J. and Bredenbeck, A. and Arzberger, F. and Mantilla, C. A. Reyes and Maurelli, F. and Unnithan, V. and Dreger, H. and Mathewos, K. and Pradhan, N. and Pernechele, C. and Paoletti, L. and Simioni, E. and Santagata, T.}, booktitle = {Proceedings of the 52nd Lunar and Planetary Science Conference (LPSC '21)}, keywords = {imported}, month = {March}, organization = {Universities Space Research Association, Lunar and Planetary Institute}, title = {Marius Hills Skylight hazard characterization as a possible landing site for lunar subsurface exploration}, year = 2021 }
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  Measuring internal quality traits in egg by 3D laser imaging Mollazade, K.; Jörissen, S.; Nüchter, A. in Journal of Food Engineering (2021). 291(02) 1–14.
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  Quality of the egg is examined before the production process in the food industry. In this study, a 3D laser scanning approach was developed to measure internal quality traits of the egg. Experiments were carried out on 450 chicken egg samples in different freshness stages. Spectroscopic analysis showed 600–700 nm would be a suitable wavelength region for laser scanning. The quasi-liquid transparency nature of the albumin introduced issues to laser scanning, which were fixed by two solutions: 1. coating of the thick albumin region with Talcum powder before scanning, and 2. training a multilayer perceptron neural network to map the 2D shape features of the thick albumin region to the actual albumin height values. Results indicated that the yolk index and Haugh unit are reliably measured using 3D scanning of the yolk part (R = 0.97 and RMSE = 0.04) and the 2D shape analysis of the thick albumin region (R = 0.84 and RMSE = 6.53), respectively.

  @article{JFOODENG2021, abstract = {Quality of the egg is examined before the production process in the food industry. In this study, a 3D laser scanning approach was developed to measure internal quality traits of the egg. Experiments were carried out on 450 chicken egg samples in different freshness stages. Spectroscopic analysis showed 600–700 nm would be a suitable wavelength region for laser scanning. The quasi-liquid transparency nature of the albumin introduced issues to laser scanning, which were fixed by two solutions: 1. coating of the thick albumin region with Talcum powder before scanning, and 2. training a multilayer perceptron neural network to map the 2D shape features of the thick albumin region to the actual albumin height values. Results indicated that the yolk index and Haugh unit are reliably measured using 3D scanning of the yolk part (R = 0.97 and RMSE = 0.04) and the 2D shape analysis of the thick albumin region (R = 0.84 and RMSE = 6.53), respectively.}, author = {Mollazade, K. and J{\"o}rissen, S. and N{\"u}chter, A.}, journal = {Journal of Food Engineering}, keywords = {myown}, month = {February}, number = {02}, pages = {1–14}, title = {Measuring internal quality traits in egg by 3D laser imaging}, volume = 291, year = 2021 }
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  RADLER -- A UNICYCLE AS A LOW-COST RADIAL LASER SCANNER Borrmann, D.; Jörissen, S.; Nüchter, A. in Proceedings of the ISPRS Congress 2021, ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences (2021). 65–72.
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  In recent years a wide range of 3D multi sensor systems for various applications has been proposed. Each of them has its own benefits and limitations. This paper proposes a modified unicycle with a 2D laser profiler attached to the wheel axle, thus creating a radial 3D scanning pattern. This novel low-cost device combines the advantages of wheeled scanning equipment with those of wearable or hand-held devices. After presenting the hardware setup and the sensor integration, the results are evaluated using four test scenarios and a terrestrial laser scanner for comparison.

  @inproceedings{ISPRSCongress2021b, abstract = {In recent years a wide range of 3D multi sensor systems for various applications has been proposed. Each of them has its own benefits and limitations. This paper proposes a modified unicycle with a 2D laser profiler attached to the wheel axle, thus creating a radial 3D scanning pattern. This novel low-cost device combines the advantages of wheeled scanning equipment with those of wearable or hand-held devices. After presenting the hardware setup and the sensor integration, the results are evaluated using four test scenarios and a terrestrial laser scanner for comparison.}, address = {Nice, France}, author = {Borrmann, D. and J{\"o}rissen, S. and N{\"u}chter, A.}, booktitle = {Proceedings of the ISPRS Congress 2021}, keywords = {imported}, number = {V-1-2021}, pages = {65–72}, series = {ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences}, title = {RADLER – A UNICYCLE AS A LOW-COST RADIAL LASER SCANNER}, year = 2021 }
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  SCOUT3D -- ein Unterwasser-Laserscanner für mobile Kartierung Bleier, M.; van der Lucht, J.; Nüchter, A. in Allgemeine Vermessungs-Nachrichten (AVN) (2021). 128(4) 171–180.
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  Dieser Beitrag stellt einen neu entwickelten Unterwasser-Laserscanner kombiniert mit einem auf GNSS basierenden System zur Bestimmung der Trajektorie vor. Dies ermöglicht es, von einem Boot aus den Grund oder Objekte in flachen Gewässern zu kartieren. Das System verfügt über eine Über- und eine Unterwasserkomponente. Über Wasser werden zwei kostengünstige Multiband-GNSS-Empfänger mit einer Antennenbasislinie von einem Meter für die RTK-Positionierung mit Kurswinkel verwendet. Die kompletten sechs Freiheitsgrade der Positionierung werden durch die Fusionierung der Satellitennavigationsdaten und einer MEMS-basierten INS bestimmt. Die 3D-Daten im Wasser werden mit einem Structured-Light-Scanner erfasst, der aus einer lichtempfindlichen Unterwasserkamera und einem grünen Kreuzlinienlaserprojektor besteht. Es werden die Entwicklung des Systems und die verwendeten Hardwarekomponenten beschrieben und erste Ergebnisse präsentiert. Hierzu wurden Testobjekte in einem Wassertank sowohl von einem Stativ aus als auch von einer bewegten, schwimmenden Plattform aus gescannt. Eine Auswertung der entstanden Punktwolken findet durch einen Vergleich mit in der Szene platzierten Prüfkörpern und in Luft erzeugten Referenzscans der Testobjekte statt. Die Experimente evaluieren Auflösungsvermögen sowie Genauigkeit der Scans.

  @article{AVN2021, abstract = {Dieser Beitrag stellt einen neu entwickelten Unterwasser-Laserscanner kombiniert mit einem auf GNSS basierenden System zur Bestimmung der Trajektorie vor. Dies ermöglicht es, von einem Boot aus den Grund oder Objekte in flachen Gewässern zu kartieren. Das System verfügt über eine Über- und eine Unterwasserkomponente. Über Wasser werden zwei kostengünstige Multiband-GNSS-Empfänger mit einer Antennenbasislinie von einem Meter für die RTK-Positionierung mit Kurswinkel verwendet. Die kompletten sechs Freiheitsgrade der Positionierung werden durch die Fusionierung der Satellitennavigationsdaten und einer MEMS-basierten INS bestimmt. Die 3D-Daten im Wasser werden mit einem Structured-Light-Scanner erfasst, der aus einer lichtempfindlichen Unterwasserkamera und einem grünen Kreuzlinienlaserprojektor besteht. Es werden die Entwicklung des Systems und die verwendeten Hardwarekomponenten beschrieben und erste Ergebnisse präsentiert. Hierzu wurden Testobjekte in einem Wassertank sowohl von einem Stativ aus als auch von einer bewegten, schwimmenden Plattform aus gescannt. Eine Auswertung der entstanden Punktwolken findet durch einen Vergleich mit in der Szene platzierten Prüfkörpern und in Luft erzeugten Referenzscans der Testobjekte statt. Die Experimente evaluieren Auflösungsvermögen sowie Genauigkeit der Scans.}, author = {Bleier, M. and van der Lucht, J. and N{\"u}chter, A.}, journal = {Allgemeine Vermessungs-Nachrichten (AVN)}, keywords = {imported}, month = {August}, number = 4, pages = {171–180}, title = {SCOUT3D – ein Unterwasser-Laserscanner für mobile Kartierung}, volume = 128, year = 2021 }
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  Self-Supervised Point Set Local Descriptors for Point Cloud Registration Yuan, Y.; Borrmann, D.; Hou, J.; Ma, Y.; Schwertfeger, S.; Nüchter, A. in Sensors (2021). 21(2) 486.
  • [ Abstract ]
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  Mapping and localization of mobile robots in an unknown environment are essential for most high-level operations like autonomous navigation or exploration. This paper presents a novel approach for combining estimated trajectories, namely curvefusion. The robot used in the experiments is equipped with a horizontally mounted 2D profiler, a constantly spinning 3D laser scanner and a GPS module. The proposed algorithm first combines trajectories from different sensors to optimize poses of the planar three degrees of freedom (DoF) trajectory, which is then fed into continuous-time simultaneous localization and mapping (SLAM) to further improve the trajectory. While state-of-the-art multi-sensor fusion methods mainly focus on probabilistic methods, our approach instead adopts a deformation-based method to optimize poses. To this end, a similarity metric for curved shapes is introduced into the robotics community to fuse the estimated trajectories. Additionally, a shape-based point correspondence estimation method is applied to the multi-sensor time calibration. Experiments show that the proposed fusion method can achieve relatively better accuracy, even if the error of the trajectory before fusion is large, which demonstrates that our method can still maintain a certain degree of accuracy in an environment where typical pose estimation methods have poor performance. In addition, the proposed time-calibration method also achieves high accuracy in estimating point correspondences.

  @article{MDPI2021, abstract = {Mapping and localization of mobile robots in an unknown environment are essential for most high-level operations like autonomous navigation or exploration. This paper presents a novel approach for combining estimated trajectories, namely curvefusion. The robot used in the experiments is equipped with a horizontally mounted 2D profiler, a constantly spinning 3D laser scanner and a GPS module. The proposed algorithm first combines trajectories from different sensors to optimize poses of the planar three degrees of freedom (DoF) trajectory, which is then fed into continuous-time simultaneous localization and mapping (SLAM) to further improve the trajectory. While state-of-the-art multi-sensor fusion methods mainly focus on probabilistic methods, our approach instead adopts a deformation-based method to optimize poses. To this end, a similarity metric for curved shapes is introduced into the robotics community to fuse the estimated trajectories. Additionally, a shape-based point correspondence estimation method is applied to the multi-sensor time calibration. Experiments show that the proposed fusion method can achieve relatively better accuracy, even if the error of the trajectory before fusion is large, which demonstrates that our method can still maintain a certain degree of accuracy in an environment where typical pose estimation methods have poor performance. In addition, the proposed time-calibration method also achieves high accuracy in estimating point correspondences.}, author = {Yuan, Y. and Borrmann, D. and Hou, J. and Ma, Y. and Schwertfeger, S. and N{\"u}chter, A.}, journal = {Sensors}, keywords = {myown}, month = {January}, number = 2, pages = 486, title = {Self-Supervised Point Set Local Descriptors for Point Cloud Registration}, volume = 21, year = 2021 }
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  Stability metrics and improved odometry prediction for tracked vehicles with tactile sensors Edlinger, R.; Föls, C.; Froschauer, R.; Nüchter, A. in IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’21) (2021). 1–6.
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  @inproceedings{SSRR2021, address = {New York, USA}, author = {Edlinger, R. and F{\"o}ls, C. and Froschauer, R. and {N{\"u}chter}, A.}, booktitle = {IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '21)}, keywords = {myown}, month = {October}, pages = {1–6}, title = {{Stability metrics and improved odometry prediction for tracked vehicles with tactile sensors}}, year = 2021 }
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  Testing AGV Mobility Control Method for MANET Coverage Optimization using Procedural Generation Sauer, C.; Lyczkowski, E.; Schmidt, M.; Nüchter, A.; Hoßfeld, T. in Proceedings of the ACM Conference MSWiM: Modeling, Analysis and Simulation of Wireless and Mobile Systems (2021).
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  In industrial applications continuous wireless connectivity of mobile clients can rarely by guaranteed. Lack of communication negatively impacts the performance of industrial automation systems, e.g. Automated Guided Vehicle (AGV) fleets. Utilizing industrial Mobile Ad-hoc NETworks (MANETs) and adaptive positioning systems can reduce the number of disconnections in these AGV fleets. Therefore the performance of the mobile systems (e.g. AGV fleet) is improved and factory efficiency increased. In this work procedural simulation is used to examine wireless communication in industrial applications. This methods enables the observation of the interaction of mobility control system, network status and robotic system performance independently from a specific environment or scenario. Novel insights on the effectiveness of ad-hoc communication in industrial applications and the correlation of AGV fleet connectedness and AGV fleet transport performance are presented. Additionally a control method is proposed, which improves the network coverage of an industrial MANET and efficiency of AGV fleets.

  @inproceedings{MSWiM_2021, abstract = {In industrial applications continuous wireless connectivity of mobile clients can rarely by guaranteed. Lack of communication negatively impacts the performance of industrial automation systems, e.g. Automated Guided Vehicle (AGV) fleets. Utilizing industrial Mobile Ad-hoc NETworks (MANETs) and adaptive positioning systems can reduce the number of disconnections in these AGV fleets. Therefore the performance of the mobile systems (e.g. AGV fleet) is improved and factory efficiency increased. In this work procedural simulation is used to examine wireless communication in industrial applications. This methods enables the observation of the interaction of mobility control system, network status and robotic system performance independently from a specific environment or scenario. Novel insights on the effectiveness of ad-hoc communication in industrial applications and the correlation of AGV fleet connectedness and AGV fleet transport performance are presented. Additionally a control method is proposed, which improves the network coverage of an industrial MANET and efficiency of AGV fleets.}, address = {Alicante, Spain}, author = {Sauer, C. and Lyczkowski, E. and Schmidt, M. and N{\"u}chter, A. and Ho{\ss}feld, T.}, booktitle = {Proceedings of the ACM Conference MSWiM: Modeling, Analysis and Simulation of Wireless and Mobile Systems}, keywords = {myown}, title = {{Testing AGV Mobility Control Method for MANET Coverage Optimization using Procedural Generation}}, year = 2021 }
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  Towards spherical robots for mobile mapping in human made environments Arzberger, F.; Bredenbeck, A.; Zevering, J.; Borrmann, D.; Nüchter, A. in ISPRS Open Journal of Photogrammetry and Remote Sensing (OJPRS) (2021). 1 100004.
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  Spherical robots are a format that has not been thoroughly explored for the application of mobile mapping. In contrast to other designs, it provides some unique advantages. Among those is a spherical shell that protects internal sensors and actuators from possible harsh environments, as well as an inherent rotation for locomotion that enables measurements in all directions. Mobile mapping always requires a high-precise pose knowledge to obtain consistent and correct environment maps. This is typically done by a combination of external reference sensors such as Global Navigation Satellite System (GNSS) measurements and inertial measurements or by coarsely estimating the pose using inertial measurement units (IMUs) and post processing the data by registering the different measurements to each other. In indoor environments, the GNSS reference is not an option. Hence many mobile mapping applications turn to the second option. An advantage of indoor environments is that human-made environments usually have a certain structure, such as parallel and perpendicular planes. We propose a registration procedure that exploits this structure by minimizing the distance of measured points to a corresponding plane. Further, we evaluate the procedure on a simulated dataset of an ideal corridor and on an experimentally acquired dataset with different motion profiles. We show that we nearly reproduce the ground truth for the simulated dataset and improve the average point-to-point distance to a reference scan in the experimental dataset. The presented algorithms are required to work completely autonomously.

  @article{JPRS_2018, abstract = {Spherical robots are a format that has not been thoroughly explored for the application of mobile mapping. In contrast to other designs, it provides some unique advantages. Among those is a spherical shell that protects internal sensors and actuators from possible harsh environments, as well as an inherent rotation for locomotion that enables measurements in all directions. Mobile mapping always requires a high-precise pose knowledge to obtain consistent and correct environment maps. This is typically done by a combination of external reference sensors such as Global Navigation Satellite System (GNSS) measurements and inertial measurements or by coarsely estimating the pose using inertial measurement units (IMUs) and post processing the data by registering the different measurements to each other. In indoor environments, the GNSS reference is not an option. Hence many mobile mapping applications turn to the second option. An advantage of indoor environments is that human-made environments usually have a certain structure, such as parallel and perpendicular planes. We propose a registration procedure that exploits this structure by minimizing the distance of measured points to a corresponding plane. Further, we evaluate the procedure on a simulated dataset of an ideal corridor and on an experimentally acquired dataset with different motion profiles. We show that we nearly reproduce the ground truth for the simulated dataset and improve the average point-to-point distance to a reference scan in the experimental dataset. The presented algorithms are required to work completely autonomously.}, author = {Arzberger, F. and Bredenbeck, A. and Zevering, J. and Borrmann, D. and N{\"u}chter, A.}, journal = {ISPRS Open Journal of Photogrammetry and Remote Sensing (OJPRS)}, keywords = {imported}, pages = 100004, title = {Towards spherical robots for mobile mapping in human made environments}, volume = 1, year = 2021 }

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  Analytical Change Detection on the KITTI Dataset Schauer, J.; Nüchter, A. in Proceedings of the 14th IEEE International Conference on Control, Automation, Robotics and Vision (ICARCV ’20) (2020).
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  We present an algorithm for explicit change detec- tion on 3D point cloud data from a mobile mapping scenario, namely the KITTI dataset. Our method is able to partition a 3D point cloud into static and dynamic points using ray traversal of a 3D voxel grid. We are thus not using a machine learning approach or RGB camera data but instead compute the intersections of the scene volume with the lines-of-sight between the sensor and the measured points. Our approach does thus not require any object detection or tracking and has comparatively low requirements on the hardware. While our earlier work focused on dense point clouds from terrestrial 3D laser scans, here we investigate its application on the sparse 3D point clouds produced by a Velodyne laser range finder in a mobile mapping scenario and compare our results to two competing implementations using the ground truth annotation from FuseMODNet for a quantitative analysis. We also introduce spherical quadtree point cloud reduction as a way to only work on less than 1\% of the original data, making processing multiple times faster while at the same time producing results with equivalent $F_1$ scores.

  @inproceedings{ICARCV2020, abstract = {We present an algorithm for explicit change detec- tion on 3D point cloud data from a mobile mapping scenario, namely the KITTI dataset. Our method is able to partition a 3D point cloud into static and dynamic points using ray traversal of a 3D voxel grid. We are thus not using a machine learning approach or RGB camera data but instead compute the intersections of the scene volume with the lines-of-sight between the sensor and the measured points. Our approach does thus not require any object detection or tracking and has comparatively low requirements on the hardware. While our earlier work focused on dense point clouds from terrestrial 3D laser scans, here we investigate its application on the sparse 3D point clouds produced by a Velodyne laser range finder in a mobile mapping scenario and compare our results to two competing implementations using the ground truth annotation from FuseMODNet for a quantitative analysis. We also introduce spherical quadtree point cloud reduction as a way to only work on less than 1\% of the original data, making processing multiple times faster while at the same time producing results with equivalent $F_1$ scores.}, address = {Shenzhen, China}, author = {Schauer, J. and N{\"u}chter, A.}, booktitle = {Proceedings of the 14th IEEE International Conference on Control, Automation, Robotics and Vision (ICARCV '20)}, keywords = {myown}, month = {December (accpeted)}, title = {{Analytical Change Detection on the KITTI Dataset}}, year = 2020 }
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  Curvefusion --- A Method for Combining Estimated Trajectories with Applications to SLAM and Time-Calibration Du, S.; Lauterbach, H. A.; Li, X.; Demisse, G. G.; Borrmann, D.; Nüchter, A. in Sensors (2020). 20(23) 6918.
  • [ Abstract ]
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  Mapping and localization of mobile robots in an unknown environment are essential for most high-level operations like autonomous navigation or exploration. This paper presents a novel approach for combining estimated trajectories, namely curvefusion. The robot used in the experiments is equipped with a horizontally mounted 2D profiler, a constantly spinning 3D laser scanner and a GPS module. The proposed algorithm first combines trajectories from different sensors to optimize poses of the planar three degrees of freedom (DoF) trajectory, which is then fed into continuous-time simultaneous localization and mapping (SLAM) to further improve the trajectory. While state-of-the-art multi-sensor fusion methods mainly focus on probabilistic methods, our approach instead adopts a deformation-based method to optimize poses. To this end, a similarity metric for curved shapes is introduced into the robotics community to fuse the estimated trajectories. Additionally, a shape-based point correspondence estimation method is applied to the multi-sensor time calibration. Experiments show that the proposed fusion method can achieve relatively better accuracy, even if the error of the trajectory before fusion is large, which demonstrates that our method can still maintain a certain degree of accuracy in an environment where typical pose estimation methods have poor performance. In addition, the proposed time-calibration method also achieves high accuracy in estimating point correspondences.

  @article{MDPI2020, abstract = {Mapping and localization of mobile robots in an unknown environment are essential for most high-level operations like autonomous navigation or exploration. This paper presents a novel approach for combining estimated trajectories, namely curvefusion. The robot used in the experiments is equipped with a horizontally mounted 2D profiler, a constantly spinning 3D laser scanner and a GPS module. The proposed algorithm first combines trajectories from different sensors to optimize poses of the planar three degrees of freedom (DoF) trajectory, which is then fed into continuous-time simultaneous localization and mapping (SLAM) to further improve the trajectory. While state-of-the-art multi-sensor fusion methods mainly focus on probabilistic methods, our approach instead adopts a deformation-based method to optimize poses. To this end, a similarity metric for curved shapes is introduced into the robotics community to fuse the estimated trajectories. Additionally, a shape-based point correspondence estimation method is applied to the multi-sensor time calibration. Experiments show that the proposed fusion method can achieve relatively better accuracy, even if the error of the trajectory before fusion is large, which demonstrates that our method can still maintain a certain degree of accuracy in an environment where typical pose estimation methods have poor performance. In addition, the proposed time-calibration method also achieves high accuracy in estimating point correspondences.}, author = {Du, S. and Lauterbach, H. A. and Li, X. and Demisse, G. G. and Borrmann, D. and N{\"u}chter, A.}, journal = {Sensors}, keywords = {myown}, month = {December}, number = 23, pages = 6918, title = {Curvefusion — A Method for Combining Estimated Trajectories with Applications to SLAM and Time-Calibration}, volume = 20, year = 2020 }
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  Different Points of View: Impact of 3D Point Cloud Reduction on QoE of Rendered Images Seufert, M.; Kargl, J.; Schauer, J.; Nüchter, A.; Hoßfeld, T. in IEEE 12th International Conference on Quality of Multimedia Experience (QoMEX) (2020). 1–6.
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  Modern photogrammetric methods as well as laser measurement systems make it easy to collect large 3D point clouds that sample objects or environments. As the recorded point clouds can be used to render computer-generated images and models, they are of particular interest in the domains of geographical and architectural engineering, as well as for computer graphics (e.g., games or virtual reality). However, point clouds have a huge storage demand, thus, point clouds shall be reduced by removing some of the points. This will inevitably also reduce the Quality of Experience (QoE) of media, which is rendered from the reduced point clouds. In this work, the impact of two different reduction methods on the QoE of rendered images is investigated from two point of views, i.e., based on ratings from both naive crowdworkers as well as point cloud experts.

  @inproceedings{QMEX2020, abstract = {Modern photogrammetric methods as well as laser measurement systems make it easy to collect large 3D point clouds that sample objects or environments. As the recorded point clouds can be used to render computer-generated images and models, they are of particular interest in the domains of geographical and architectural engineering, as well as for computer graphics (e.g., games or virtual reality). However, point clouds have a huge storage demand, thus, point clouds shall be reduced by removing some of the points. This will inevitably also reduce the Quality of Experience (QoE) of media, which is rendered from the reduced point clouds. In this work, the impact of two different reduction methods on the QoE of rendered images is investigated from two point of views, i.e., based on ratings from both naive crowdworkers as well as point cloud experts.}, author = {{Seufert}, M. and {Kargl}, J. and {Schauer}, J. and {N{\"u}chter}, A. and {Hoßfeld}, T.}, booktitle = {IEEE 12th International Conference on Quality of Multimedia Experience (QoMEX)}, keywords = {myown}, month = {may}, pages = {1–6}, title = {Different Points of View: Impact of 3D Point Cloud Reduction on QoE of Rendered Images}, year = 2020 }
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  Feature Detection With a Constant FAR in Sparse 3-D Point Cloud Data Lühr, D.; Adams, M.; Houshiar, H.; Borrmann, D.; Nüchter, A. in IEEE Transactions on Geoscience and Remote Sensing (2020). 58(3) 1877–1891.
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  The detection of markers or reflectors within point cloud data (PCD) is often used for 3-D scan registration, mapping, and 3-D environmental modeling. However, the reliable detection of such artifacts is diminished when PCD is sparse and corrupted by detection and spatial errors, for example, when the sensing environment is contaminated by high dust levels, such as in mines. In the radar literature, constant false alarm rate (CFAR) processors provide solutions for extracting features within noisy data; however, their direct application to sparse, 3-D PCD is limited due to the difficulty in defining a suitable noise window. Therefore, in this article, CFAR detectors are derived, which are capable of processing a 2-D projected version of the 3-D PCD or which can directly process the 3-D PCD itself. Comparisons of their robustness, with respect to data sparsity, are made with various state-of-the-art feature detection methods, such as the Canny edge detector and random sampling consensus (RANSAC) shape detection methods.

  @article{tgrs2020, abstract = {The detection of markers or reflectors within point cloud data (PCD) is often used for 3-D scan registration, mapping, and 3-D environmental modeling. However, the reliable detection of such artifacts is diminished when PCD is sparse and corrupted by detection and spatial errors, for example, when the sensing environment is contaminated by high dust levels, such as in mines. In the radar literature, constant false alarm rate (CFAR) processors provide solutions for extracting features within noisy data; however, their direct application to sparse, 3-D PCD is limited due to the difficulty in defining a suitable noise window. Therefore, in this article, CFAR detectors are derived, which are capable of processing a 2-D projected version of the 3-D PCD or which can directly process the 3-D PCD itself. Comparisons of their robustness, with respect to data sparsity, are made with various state-of-the-art feature detection methods, such as the Canny edge detector and random sampling consensus (RANSAC) shape detection methods.}, author = {{L{\"u}hr}, D. and {Adams}, M. and {Houshiar}, H. and {Borrmann}, D. and {N{\"u}chter}, A.}, journal = {IEEE Transactions on Geoscience and Remote Sensing}, keywords = {author}, month = {March}, number = 3, pages = {1877–1891}, title = {{Feature Detection With a Constant FAR in Sparse 3-D Point Cloud Data}}, volume = 58, year = 2020 }
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  Formations of Small Satellites to Realize Sensor Networks for Earth Observation Schilling, K.; Nüchter, A. in Proceedings of the 24th IMEKO TC4 International Symposium (2020).
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  At the level of small satellites with a mass of a few kilograms all capabilities of self-organizing sensor networks for Earth observation can be realized. Photogrammetry methods enable sensor data fusion to generate 3-dimensional images of a target area. Here appropriate satellite position information in combination with attitude determination and control provides precision pointing accuracies to generate suitable input for subsequent data processing. This way, on small satellites efficient methods for distributed sensor systems in orbit can be implemented.

  @inproceedings{IMEKO2020, abstract = {At the level of small satellites with a mass of a few kilograms all capabilities of self-organizing sensor networks for Earth observation can be realized. Photogrammetry methods enable sensor data fusion to generate 3-dimensional images of a target area. Here appropriate satellite position information in combination with attitude determination and control provides precision pointing accuracies to generate suitable input for subsequent data processing. This way, on small satellites efficient methods for distributed sensor systems in orbit can be implemented.}, address = {Palermo, Italy (online)}, author = {Schilling, K. and N{\"u}chter, A.}, booktitle = {Proceedings of the 24th IMEKO TC4 International Symposium}, keywords = {myown}, month = {September}, publisher = {The International Measurement Confederation}, title = {Formations of Small Satellites to Realize Sensor Networks for Earth Observation}, year = 2020 }
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  Laserscanbasierte Ändreungsanalyse am Beispiel der Langen Anna auf Helgoland Borrmann, D.; Lauterbach, H.; Houshiar, H.; Rossi, A. Pio; Unnitham, V.; Nüchter, A. in Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beiträge der Oldenburger 3D-Tage 2020, Jade Hochschule (2020). 186–197.
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  Die "`Lange Anna"' ist das Wahrzeichen der Deutschen Hochseeinsel Helgoland. Durch seinen Standort an der Nordspitze der Insel ist der Buntsandsteinfelsen durch von Wind und Wasser verursachte Erosionen gefährdet. In einem Zeitraum von fünf Jahren wurden wiederholt an mehreren Standorten um die "`Lange Anna"' mit einem Riegl VZ-400 Laserscans aufgenommen. Dieser Beitrag evaluiert Methoden, um die Veränderungen automatisch zu dokumentieren und zu analysieren. Dies beinhaltet zwei grundlegende Arbeitsschritte, die in 3DTK (The 3D Toolkit) umgesetzt sind. Zuerst werden die Daten von mehreren Standpunkten in einem gemeinsamen Koordinatensystem registriert. Anschließend wird die Änderung am Gestein quantitativ erfasst und beschrieben. Dieser zweite Arbeitsschritt stellt den Schwerpunkt des Beitrags dar. Zwei Distanzmaße werden für diesen Zweck evaluiert, Punkt-zu-Punkt und Punkt-zu-Ebene-Distanzen.

  @inproceedings{3DTAGE2020_1, abstract = {Die "`Lange Anna"' ist das Wahrzeichen der Deutschen Hochseeinsel Helgoland. Durch seinen Standort an der Nordspitze der Insel ist der Buntsandsteinfelsen durch von Wind und Wasser verursachte Erosionen gefährdet. In einem Zeitraum von fünf Jahren wurden wiederholt an mehreren Standorten um die "`Lange Anna"' mit einem Riegl VZ-400 Laserscans aufgenommen. Dieser Beitrag evaluiert Methoden, um die Veränderungen automatisch zu dokumentieren und zu analysieren. Dies beinhaltet zwei grundlegende Arbeitsschritte, die in 3DTK (The 3D Toolkit) umgesetzt sind. Zuerst werden die Daten von mehreren Standpunkten in einem gemeinsamen Koordinatensystem registriert. Anschließend wird die Änderung am Gestein quantitativ erfasst und beschrieben. Dieser zweite Arbeitsschritt stellt den Schwerpunkt des Beitrags dar. Zwei Distanzmaße werden für diesen Zweck evaluiert, Punkt-zu-Punkt und Punkt-zu-Ebene-Distanzen.}, author = {Borrmann, D. and Lauterbach, H. and Houshiar, H. and Rossi, A. Pio and Unnitham, V. and N{\"u}chter, A.}, booktitle = {Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beitr{\"a}ge der Oldenburger 3D-Tage 2020, Jade Hochschule}, keywords = {imported}, month = {February}, pages = {186–197}, title = {{Laserscanbasierte {\"A}ndreungsanalyse am Beispiel der Langen Anna auf Helgoland}}, year = 2020 }
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  RADLER -- ein Einrad als RADialer LasERscanner Borrmann, D.; Jörissen, S.; Nüchter, A. in Allgemeine Vermessungs-Nachrichten (AVN) (2020). 127(1) 18–27.
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  Es wird ein modifiziertes Einrad als Träger eines Multisensorsystems vorgestellt, bei dem ein an der Radachse befestigter 2D-Profil-Laserscanner ein radiales 3D-Scanpattern erzeugt. Dieses neuartige, kosten­ günstige Multisensorsystem verbindet die Vorteile von radgetriebenen Plattformen mit denen von Handscannern. Nach der Vorstellung des Hardwareaufbaus und der Sensorintegration werden die Ergebnisse aus vier Testszenarien präsentiert und bewertet.

  @article{AVN2020, abstract = {Es wird ein modifiziertes Einrad als Träger eines Multisensorsystems vorgestellt, bei dem ein an der Radachse befestigter 2D-Profil-Laserscanner ein radiales 3D-Scanpattern erzeugt. Dieses neuartige, kosten­ günstige Multisensorsystem verbindet die Vorteile von radgetriebenen Plattformen mit denen von Handscannern. Nach der Vorstellung des Hardwareaufbaus und der Sensorintegration werden die Ergebnisse aus vier Testszenarien präsentiert und bewertet.}, author = {Borrmann, D. and J{\"o}rissen, S. and N{\"u}chter, A.}, journal = {Allgemeine Vermessungs-Nachrichten (AVN)}, keywords = {myown}, month = {February}, number = 1, pages = {18–27}, title = {{RADLER – ein Einrad als RADialer LasERscanner}}, volume = 127, year = 2020 }
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  SCOUT3D -- ein Unterwasser-Laserscanner für mobile Kartierung Bleier, M.; van der Lucht, J.; Nüchter, A. in Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beiträge der Oldenburger 3D-Tage 2020, Jade Hochschule (2020). 82–93.
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  Diese Arbeit stellt einen neu entwickelten Unterwasserlaserscanner kombiniert mit einem auf GNSS basierenden System zur Bestimmung der Trajektorie vor. Dies ermöglicht es, von einem Boot aus, den Grund oder Objekte in flachen Gewässern zu kartieren. Das System verfügt über eine Über- und eine Unterwasserkomponente. Über Wasser werden zwei kostengünstige Multiband-GNSS-Empfänger mit einer Antennenbasislinie von einem Meter für die RTK-Positionierung mit Kurswinkel verwendet. Die kompletten sechs Freiheitsgrade der Positionierung werden durch die Fusionierung der Satellitennavigationsdaten und einer MEMS-basierten INS bestimmt. Die 3D-Daten werden in Wasser mit einem Structured-Light-Scanner erfasst, der aus einer lichtempfindlichen Unterwasserkamera und einem grünen Kreuzlinienlaserprojektor besteht. Es wird die Entwicklung des Systems und die verwendeten Hardwarekomponenten beschrieben und erste Ergebnisse präsentiert. Hierzu wurde ein großes Testobjekt ein einem Wassertank sowohl von einem Stativ aus, als auch von einer bewegten, schwimmenden Plattform aus gescannt. Eine Auswertung der entstanden Punktwolken findet durch einen Vergleich mit in der Szene platzierten Prüfkörpern und in Luft erzeugten Referenzscans der Testobjekte statt.

  @inproceedings{3DTAGE2020_2, abstract = {Diese Arbeit stellt einen neu entwickelten Unterwasserlaserscanner kombiniert mit einem auf GNSS basierenden System zur Bestimmung der Trajektorie vor. Dies ermöglicht es, von einem Boot aus, den Grund oder Objekte in flachen Gewässern zu kartieren. Das System verfügt über eine Über- und eine Unterwasserkomponente. Über Wasser werden zwei kostengünstige Multiband-GNSS-Empfänger mit einer Antennenbasislinie von einem Meter für die RTK-Positionierung mit Kurswinkel verwendet. Die kompletten sechs Freiheitsgrade der Positionierung werden durch die Fusionierung der Satellitennavigationsdaten und einer MEMS-basierten INS bestimmt. Die 3D-Daten werden in Wasser mit einem Structured-Light-Scanner erfasst, der aus einer lichtempfindlichen Unterwasserkamera und einem grünen Kreuzlinienlaserprojektor besteht. Es wird die Entwicklung des Systems und die verwendeten Hardwarekomponenten beschrieben und erste Ergebnisse präsentiert. Hierzu wurde ein großes Testobjekt ein einem Wassertank sowohl von einem Stativ aus, als auch von einer bewegten, schwimmenden Plattform aus gescannt. Eine Auswertung der entstanden Punktwolken findet durch einen Vergleich mit in der Szene platzierten Prüfkörpern und in Luft erzeugten Referenzscans der Testobjekte statt.}, author = {Bleier, M. and van der Lucht, J. and N{\"u}chter, A.}, booktitle = {Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beitr{\"a}ge der Oldenburger 3D-Tage 2020, Jade Hochschule}, keywords = {imported}, month = {February}, pages = {82–93}, title = {{SCOUT3D – ein Unterwasser-Laserscanner für mobile Kartierung}}, year = 2020 }
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  Signed Distance Based Reconstruction for Exploration and Change Detection in Underground Mining Disaster Prevention Koch, P.; Engelhardt, H.; May, S.; Schmidpeter, M.; Ziegler, J.; Nüchter, A. in IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’20) (2020). 1–6.
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  This publication describes an application of a Truncated Signed Distance Mapping approach for disaster intervention in underground mine shafts through geometrical change detection of the shaft walls. The paper describes two main problems of such an approach (aligning two potentially huge point clouds and automatic change detection by comparing the reconstructed volumes) and explains in detail the proposed solution.

  @inproceedings{SSRR2020, abstract = {This publication describes an application of a Truncated Signed Distance Mapping approach for disaster intervention in underground mine shafts through geometrical change detection of the shaft walls. The paper describes two main problems of such an approach (aligning two potentially huge point clouds and automatic change detection by comparing the reconstructed volumes) and explains in detail the proposed solution.}, author = {Koch, P. and Engelhardt, H. and May, S. and Schmidpeter, M. and Ziegler, J. and {N{\"u}chter}, A.}, booktitle = {IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '20)}, keywords = {imported}, month = {November}, pages = {1–6}, title = {{Signed Distance Based Reconstruction for Exploration and Change Detection in Underground Mining Disaster Prevention}}, year = 2020 }

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  3D UNDERWATER MINE MODELLING IN THE VAMOS PROJECT Bleier, M.; Almeida, C.; Ferreira, A.; Pereira, R.; Matias, B.; Almeida, J.; Pidgeon, J.; van der Lucht, J.; Schilling, K.; Martins, A.; Silva, E.; Nüchter, A. in Proceedings of the 2nd ISPRS International Workshop Underwater 3D Recording \& Modelling: A tool for modern applications and CH recording, ISPRS Archives Photogrammetry and Remote Senssing Spatial Information Science, Volume XLII-2/W10 (2019). 105–112.
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  The project Viable Alternative Mine Operating System (VAMOS) develops a novel underwater mining technique for extracting inland mineral deposits in flooded open-cut mines. From a floating launch and recovery vessel a remotely-operated underwater mining vehicle with a roadheader cutting machine is deployed. The cut material is transported to the surface via a flexible riser hose. Since there is no direct intervisibility between the operator and the mining machine, the data of the sensor systems can only be perceived via a computer interface. Therefore, part of the efforts in the project focus on enhancing the situational awareness of the operator by providing a 3D model of the mine combined with representations of the mining equipment and sensor data. We present a method how a positioning and navigation system, perception system and mapping system can be used to create a replica of the physical system and mine environment in Virtual Reality (VR) in order to assist remote control. This approach is beneficial because it allows visualizing different sensor information and data in a consistent interface, and enables showing the complete context of the mining site even if only part of the mine is currently observed by surveying equipment. We demonstrate how the system is used during tele-operation and show results achieved during the field trials of the complete system in Silvermines, Ireland.

  @inproceedings{ISPRS_3DUW, abstract = {The project Viable Alternative Mine Operating System (VAMOS) develops a novel underwater mining technique for extracting inland mineral deposits in flooded open-cut mines. From a floating launch and recovery vessel a remotely-operated underwater mining vehicle with a roadheader cutting machine is deployed. The cut material is transported to the surface via a flexible riser hose. Since there is no direct intervisibility between the operator and the mining machine, the data of the sensor systems can only be perceived via a computer interface. Therefore, part of the efforts in the project focus on enhancing the situational awareness of the operator by providing a 3D model of the mine combined with representations of the mining equipment and sensor data. We present a method how a positioning and navigation system, perception system and mapping system can be used to create a replica of the physical system and mine environment in Virtual Reality (VR) in order to assist remote control. This approach is beneficial because it allows visualizing different sensor information and data in a consistent interface, and enables showing the complete context of the mining site even if only part of the mine is currently observed by surveying equipment. We demonstrate how the system is used during tele-operation and show results achieved during the field trials of the complete system in Silvermines, Ireland.}, address = {Limassol, Cyprus}, author = {Bleier, M. and Almeida, C. and Ferreira, A. and Pereira, R. and Matias, B. and Almeida, J. and Pidgeon, J. and van der Lucht, J. and Schilling, K. and Martins, A. and Silva, E. and N{\"u}chter, A.}, booktitle = {Proceedings of the 2nd ISPRS International Workshop Underwater 3D Recording \& Modelling: A tool for modern applications and CH recording}, keywords = {myown}, month = {may}, pages = {105–112}, series = {ISPRS Archives Photogrammetry and Remote Senssing Spatial Information Science, Volume XLII-2/W10}, title = {{3D UNDERWATER MINE MODELLING IN THE VAMOS PROJECT}}, year = 2019 }
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  A low cost underwater test environment van der Lucht, J.; Bleier, M.; Nüchter, A. in Proceedings of LowCost 3D 2019, ISPRS Int. Archieves Photogrammetry and Remote Sensing, Spatial Inf. Sci., XLII-2/W17 (2019). 399–404.
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  In this paper we present the setup of a low cost underwater test environment. The employed materials and structures are described as well as the lessons learned during operations and experiments conducted in the water tank. We provide the bill of materials and a break-down of the costs involved in setting up the test site. The goal was to build a low cost test environment for underwater applications, because our lab is around 40 minutes by car from the nearest lake. Also a natural lake is not an optimal location for first test and experiments, because the access to the water is difficult and logistics of equipment is time consuming. This work aims to describe what experiences we have gained during the time of construction. Which materials we used and what we would do differently next time. Furthermore, we describe the idea and process to place calibration markers inside the container and how the water thwarted our plan. We show that it is possible to realize a useful test environment for underwater experiments for less than Euro 20.000.

  @inproceedings{LC2019, abstract = {In this paper we present the setup of a low cost underwater test environment. The employed materials and structures are described as well as the lessons learned during operations and experiments conducted in the water tank. We provide the bill of materials and a break-down of the costs involved in setting up the test site. The goal was to build a low cost test environment for underwater applications, because our lab is around 40 minutes by car from the nearest lake. Also a natural lake is not an optimal location for first test and experiments, because the access to the water is difficult and logistics of equipment is time consuming. This work aims to describe what experiences we have gained during the time of construction. Which materials we used and what we would do differently next time. Furthermore, we describe the idea and process to place calibration markers inside the container and how the water thwarted our plan. We show that it is possible to realize a useful test environment for underwater experiments for less than Euro 20.000.}, address = {Strasbourg, France}, author = {van der Lucht, J. and Bleier, M. and N{\"u}chter, A.}, booktitle = {Proceedings of LowCost 3D 2019}, keywords = {imported}, month = {November}, pages = {399–404}, series = {ISPRS Int. Archieves Photogrammetry and Remote Sensing, Spatial Inf. Sci., XLII-2/W17}, title = {A low cost underwater test environment}, year = 2019 }
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  Imaging the subsurface of planetary volcanic analogues using ambient seismic noise data at the Tinguatón Volcano (Lanzarote, Canary Islands) Torrese, P.; Rossi, A. Pio; Unnithan, V.; Borrmann, D.; Lauterbach, H.; Luzzi, E.; Pozzobon, R.; Sauro, F.; Bessone, L.; Nüchter, A. in Proceedings of the EGU General Assembly 2019, Poster: New mission concepts, enabling technologies and terrestrial analogue studies for planetary explorationn (2019).
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  @inproceedings{EGU2019, address = {Vienna, Austria}, author = {Torrese, P. and Rossi, A. Pio and Unnithan, V. and Borrmann, D. and Lauterbach, H. and Luzzi, E. and Pozzobon, R. and Sauro, F. and Bessone, L. and N{\"u}chter, A.}, booktitle = {Proceedings of the EGU General Assembly 2019, Poster: New mission concepts, enabling technologies and terrestrial analogue studies for planetary explorationn}, keywords = {myown}, month = {April}, number = {EGU2018-18492}, title = {{Imaging the subsurface of planetary volcanic analogues using ambient seismic noise data at the Tinguatón Volcano (Lanzarote, Canary Islands)}}, year = 2019 }
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  Korrektur der Brechung an der Wasseroberfläche beim triangulationsbasierten 3D-Laserscannen van der Lucht, J.; Bleier, M.; Leutert, F.; Schilling, K.; Nüchter, A. in Allgemeine Vermessungs-Nachrichten (AVN) (2019). 126 43–52.
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  Die vorliegende Arbeit beschäftigt sich mit der Korrektur der Brechung an der Wasseroberfläche beim triangulationsbasierten 3D Laserscannen. Hierzu wurde eine Methode entwickelt, um mit einem Structured Light (SL) System 3D-Daten von teilweise mit Wasser bedeckten Strukturen anzufertigen und die dabei entstehende Brechung an der Wasseroberfläche zu korrigieren. Diese wurde anschließend in einem Versuchsaufbau evaluiert. Der Scanner wurde dabei an einem KUKA KR-16 Manipulatorarm befestigt, um den Scanner gleichmäßig, definiert und wiederholbar zu bewegen. Die Bewegungen des Scanners wurden dabei durch ein externes Trackingsystem erfasst. Ebenfalls wurde bei diesen Versuchen der Einfluss verschiedener Einstrahlwinkel betrachtet. Zu diesem Zweck wurde der Scanner in verschiedenen Winkeln relativ zur Wasseroberfläche positioniert. Durch die entwickelte Methode konnten Fehler durch die Brechung an der Wasseroberfläche erfolgreich korrigiert werden. Außerdem konnte die Lage der Wasseroberfläche ohne externe Markierungen aus den 3D-Daten bestimmt werden.

  @article{AVN2019, abstract = {Die vorliegende Arbeit besch{\"a}ftigt sich mit der Korrektur der Brechung an der Wasseroberfl{\"a}che beim triangulationsbasierten 3D Laserscannen. Hierzu wurde eine Methode entwickelt, um mit einem Structured Light (SL) System 3D-Daten von teilweise mit Wasser bedeckten Strukturen anzufertigen und die dabei entstehende Brechung an der Wasseroberfl{\"a}che zu korrigieren. Diese wurde anschließend in einem Versuchsaufbau evaluiert. Der Scanner wurde dabei an einem KUKA KR-16 Manipulatorarm befestigt, um den Scanner gleichm{\"a}ßig, definiert und wiederholbar zu bewegen. Die Bewegungen des Scanners wurden dabei durch ein externes Trackingsystem erfasst. Ebenfalls wurde bei diesen Versuchen der Einfluss verschiedener Einstrahlwinkel betrachtet. Zu diesem Zweck wurde der Scanner in verschiedenen Winkeln relativ zur Wasseroberfl{\"a}che positioniert. Durch die entwickelte Methode konnten Fehler durch die Brechung an der Wasseroberfl{\"a}che erfolgreich korrigiert werden. Außerdem konnte die Lage der Wasseroberfl{\"a}che ohne externe Markierungen aus den 3D-Daten bestimmt werden.}, author = {van der Lucht, J. and Bleier, M. and Leutert, F. and Schilling, K. and N{\"u}chter, A.}, journal = {Allgemeine Vermessungs-Nachrichten (AVN)}, keywords = {myown}, month = {March}, pages = {43–52}, title = {{Korrektur der Brechung an der Wasseroberfl{\"a}che beim triangulationsbasierten 3D-Laserscannen}}, volume = 126, year = 2019 }
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  MARC -- Modular Autonomous Adaptable Robot Concept Edlinger, R.; Nüchter, A. in IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’19) (2019). 1–7.
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  The paper introduces a novel modular and adaptable payload concept for plugging in sensor and actuator platforms such as 3D LIDAR and visual sensor systems and robot manipulator and gripper systems. Integration, programming and operation of heterogeneous robot systems (such as mobile manipulators or robots in a machine network) are very complex tasks for plant operators. Heterogeneous system components have to be orchestrated (via proprietary interfaces) by higher-level control systems. Robot programs are created offline, in proprietary tools, and used through macros. System components are generally not compatible and interchangeable across manufacturers. These have to be programmed separately in manufacturer-specific tools. Cross-component debugging is difficult. The operation of complex systems is difficult, requires intensive training, and is currently limited to simple graphical user interfaces (GUI). As part of process optimization, it is usually necessary to optimize process points during the start-up phase. This requires highly skilled personnel capable of robot programming at the plant operators site. The combination of heterogeneous robot modules results in many new hazardous situations. It is therefore necessary to include an appropriate safety concept. The goal is to design a robot payload concept with a plug-and-play approach to be used as a modular and flexible unit. This shall reduce the effort for system integration and sensor calibrating significantly and provide a customized perception of the environment during certain work processes. The modular, autonomous and adaptable robot concept with several sensors and hardware components was implemented as a prototype on a rescue robot. The modules have already been integrated on other autonomous vehicles for exploration and dexterity tasks.

  @inproceedings{SSRR2019_2, abstract = {The paper introduces a novel modular and adaptable payload concept for plugging in sensor and actuator platforms such as 3D LIDAR and visual sensor systems and robot manipulator and gripper systems. Integration, programming and operation of heterogeneous robot systems (such as mobile manipulators or robots in a machine network) are very complex tasks for plant operators. Heterogeneous system components have to be orchestrated (via proprietary interfaces) by higher-level control systems. Robot programs are created offline, in proprietary tools, and used through macros. System components are generally not compatible and interchangeable across manufacturers. These have to be programmed separately in manufacturer-specific tools. Cross-component debugging is difficult. The operation of complex systems is difficult, requires intensive training, and is currently limited to simple graphical user interfaces (GUI). As part of process optimization, it is usually necessary to optimize process points during the start-up phase. This requires highly skilled personnel capable of robot programming at the plant operators site. The combination of heterogeneous robot modules results in many new hazardous situations. It is therefore necessary to include an appropriate safety concept. The goal is to design a robot payload concept with a plug-and-play approach to be used as a modular and flexible unit. This shall reduce the effort for system integration and sensor calibrating significantly and provide a customized perception of the environment during certain work processes. The modular, autonomous and adaptable robot concept with several sensors and hardware components was implemented as a prototype on a rescue robot. The modules have already been integrated on other autonomous vehicles for exploration and dexterity tasks.}, author = {{Edlinger}, R. and {N{\"u}chter}, A.}, booktitle = {IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '19)}, keywords = {myown}, month = {September}, pages = {1–7}, title = {{MARC – Modular Autonomous Adaptable Robot Concept}}, year = 2019 }
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  Mobile mapping of the La Corona lavatube on Lanzarote Lauterbach, H. A.; Borrmann, D.; Nüchter, A.; Rossi, A. P.; Unnithan, V.; Torrese, P.; Pozzobon, R. in Proceedings of the ISPRS Geospatial Week 2019, Laserscanning 2019, ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., IV-2/W5 (2019). 381–387.
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  Planetary surfaces consist of rough terrain and cave-like environments. Future planetary exploration demands for accurate mapping. However, recent backpack mobile mapping systems are mostly tested in structured, indoor environments. This paper evaluates the use of a backpack mobile mapping system in a cave-like environment. The experiments demonstrate the abilities of an continuous-time optimization approach by mapping part of a lavatube of the La Corona volcano system on Lanzarote. We compare two strategies for trajectory estimation relying either on 2D or 3D laser scanners and show that a 3D laser scanner substantially improved the final results.

  @inproceedings{LS2019, abstract = {Planetary surfaces consist of rough terrain and cave-like environments. Future planetary exploration demands for accurate mapping. However, recent backpack mobile mapping systems are mostly tested in structured, indoor environments. This paper evaluates the use of a backpack mobile mapping system in a cave-like environment. The experiments demonstrate the abilities of an continuous-time optimization approach by mapping part of a lavatube of the La Corona volcano system on Lanzarote. We compare two strategies for trajectory estimation relying either on 2D or 3D laser scanners and show that a 3D laser scanner substantially improved the final results.}, address = {Enschede, Netherlands}, author = {Lauterbach, H. A. and Borrmann, D. and N{\"u}chter, A. and Rossi, A. P. and Unnithan, V. and Torrese, P. and Pozzobon, R.}, booktitle = {Proceedings of the ISPRS Geospatial Week 2019, Laserscanning 2019}, keywords = {myown}, month = {June}, pages = {381–387}, series = {ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., IV-2/W5}, title = {Mobile mapping of the La Corona lavatube on Lanzarote}, year = 2019 }
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  Position and orientation of sensors for unmanned vehicle systems Nüchter, A. in Unmanned Vehicle Systems for Geomatics -- Towards Robotic Mapping, P. Patias, C. Armenakis (eds.) (2019).
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  @incollection{Geomatics2019, author = {N{\"u}chter, A.}, booktitle = {Unmanned Vehicle Systems for Geomatics – Towards Robotic Mapping}, editor = {Patias, P. and Armenakis, C.}, keywords = {myown}, publisher = {Whittles Publishing}, title = {Position and orientation of sensors for unmanned vehicle systems}, year = 2019 }
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  Projection based dynamic point cloud compression using 3DTK toolkit and H.265/HEVC Dumic, E.; Bjelopera, A.; Nüchter, A. in Proceedings of the 2nd International Colloquium on Smart Grid Metrology (SMAGRIMET’’19) (2019). 1–4.
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  This paper presents novel compression method for dynamic point clouds based on projections and the H.265/HEVC video coder. We used 3DTK - The 3D Toolkit to create equirect-angular projection images and x265 as H.265/HEVC coder, to compress and extract created projection images. Compression was introduced in 3DTK generated projection image size (differ-ent pixel size, but compatible with later video compression), as well as lossless/lossy video compression. Visual inspection shows better results for compression only using different projection resolution, with lossless video compression. Lossy video compression adds noise and creates additional points, resulting in lower visual quality.

  @inproceedings{SMGM_2019, abstract = {This paper presents novel compression method for dynamic point clouds based on projections and the H.265/HEVC video coder. We used 3DTK - The 3D Toolkit to create equirect-angular projection images and x265 as H.265/HEVC coder, to compress and extract created projection images. Compression was introduced in 3DTK generated projection image size (differ-ent pixel size, but compatible with later video compression), as well as lossless/lossy video compression. Visual inspection shows better results for compression only using different projection resolution, with lossless video compression. Lossy video compression adds noise and creates additional points, resulting in lower visual quality.}, address = {Split, Croatia}, author = {{Dumic}, E. and {Bjelopera}, A. and {N{\"u}chter}, A.}, booktitle = {Proceedings of the 2nd International Colloquium on Smart Grid Metrology (SMAGRIMET''19)}, keywords = {myown}, month = {April}, pages = {1–4}, publisher = {IEEE Xplore}, title = {{Projection based dynamic point cloud compression using 3DTK toolkit and H.265/HEVC}}, year = 2019 }
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  RADLER -- Ein Einrad als RADialer LasER Scanner Borrmann, D.; Jörissen, S.; Nüchter, A. in Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beiträge der Oldenburger 3D-Tage 2019, Jade Hochschule (2019). 12–21.
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  Die Weiterentwicklung in der 3D-Messtechnik hat in den letzten Jahren eine Vielzahl an unterschiedlichen Messgeräten zu 3D-Umgebungserfassung hervorgebracht, jedes davon mit seinen eigenen Vorzügen und Schwächen. Diese Arbeit stellt ein modifiziertes Einrad vor, bei dem ein an der Radachse befestigter 2D Laserscanner ein radiales 3D Scanpattern erzeugt. Dieses neuartige, kostengünstige Messgerät verbindet die Vorteile von radgetriebenen Scangeräten mit denen von Handscannern. Nach der Vorstellung des Hardwareaufbaus und der Sensorintegration werden die Ergebnisse anhand von drei Testszenarien ausgewertet und mit den Daten eines terrestrischen 3D-Laserscanners verglichen.

  @inproceedings{3DTAGE2019, abstract = {Die Weiterentwicklung in der 3D-Messtechnik hat in den letzten Jahren eine Vielzahl an unterschiedlichen Messgeräten zu 3D-Umgebungserfassung hervorgebracht, jedes davon mit seinen eigenen Vorzügen und Schwächen. Diese Arbeit stellt ein modifiziertes Einrad vor, bei dem ein an der Radachse befestigter 2D Laserscanner ein radiales 3D Scanpattern erzeugt. Dieses neuartige, kostengünstige Messgerät verbindet die Vorteile von radgetriebenen Scangeräten mit denen von Handscannern. Nach der Vorstellung des Hardwareaufbaus und der Sensorintegration werden die Ergebnisse anhand von drei Testszenarien ausgewertet und mit den Daten eines terrestrischen 3D-Laserscanners verglichen.}, author = {Borrmann, D. and J{\"o}rissen, S. and N{\"u}chter, A.}, booktitle = {Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beitr{\"a}ge der Oldenburger 3D-Tage 2019, Jade Hochschule}, keywords = {myown}, month = {February}, pages = {12–21}, title = {{RADLER – Ein Einrad als RADialer LasER Scanner}}, year = 2019 }
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  Satellite Technology: An international, interdisciplinary master program with focus on hands-on experiences Schilling, K.; Nüchter, A.; Montenegro, S. in Proceedings 70th International Astronautical Congress (2019).
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  Within the spacecraft engineering programs at Bachelor, Master and PhD level University Wuerzburg started 2018 the new program Satellite Technology. As main progress in modern spacecraft engineering focusses on advanced electronics and software, this program is realized within the Computer Science Institute. Specific emphasis is on modern microelectronic and data processing systems onboard the satellites, as well as algorithmic aspects in the application sectors related to Earth observation, telecommunication and scientific exploration. Specific emphasis is on hands-on experiences by the design of FloatSats, CanSats and educational CubeSats in order to complement lectures by practical implementation aspects. The students are offered excursions to space research institutes (DLR, Fraunhofer, Max-Planck institutes) and to industry (Airbus Space, OHB,...). In the breacks between lecture periods they get offered opportunities to participate in one of the ongoing satellite reallization projects. As there are currently 18 small satellites implemented in Wuerzburg there are excellent opportunities for interesting hands-on experiences. In 'Satellite Technology' 12 Bavarian partners (Universities, research institutes and industry) addressing space applications cooperate within the Elitenetzwerk Bayern to offer to the students in English language a program with emphasis on small satellite design aspects. In addition the most relevant application fields in Earth observation and in telecommunication are well represented in the program. International partner universities are integrated to allow the students to include related study segments abroad into the curricullum, in particular for Master thesis work. This contribution adresses the international university cooperation, the contents of the curriculum, as well as the specific challenges and experiences acquired in setting up this international program.

  @inproceedings{IAC2019, abstract = {Within the spacecraft engineering programs at Bachelor, Master and PhD level University Wuerzburg started 2018 the new program Satellite Technology. As main progress in modern spacecraft engineering focusses on advanced electronics and software, this program is realized within the Computer Science Institute. Specific emphasis is on modern microelectronic and data processing systems onboard the satellites, as well as algorithmic aspects in the application sectors related to Earth observation, telecommunication and scientific exploration. Specific emphasis is on hands-on experiences by the design of FloatSats, CanSats and educational CubeSats in order to complement lectures by practical implementation aspects. The students are offered excursions to space research institutes (DLR, Fraunhofer, Max-Planck institutes) and to industry (Airbus Space, OHB,...). In the breacks between lecture periods they get offered opportunities to participate in one of the ongoing satellite reallization projects. As there are currently 18 small satellites implemented in Wuerzburg there are excellent opportunities for interesting hands-on experiences. In 'Satellite Technology' 12 Bavarian partners (Universities, research institutes and industry) addressing space applications cooperate within the Elitenetzwerk Bayern to offer to the students in English language a program with emphasis on small satellite design aspects. In addition the most relevant application fields in Earth observation and in telecommunication are well represented in the program. International partner universities are integrated to allow the students to include related study segments abroad into the curricullum, in particular for Master thesis work. This contribution adresses the international university cooperation, the contents of the curriculum, as well as the specific challenges and experiences acquired in setting up this international program.}, address = {Washington D.C., USA}, author = {Schilling, K. and N{\"u}chter, A. and Montenegro, S.}, booktitle = {Proceedings 70th International Astronautical Congress}, keywords = {myown}, month = {October}, number = {IAC-19 E1.4.54918}, title = {Satellite Technology: An international, interdisciplinary master program with focus on hands-on experiences}, year = 2019 }
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  SCOUT3D -- An underwater laser scanning system for mobile mapping Bleier, M.; v.d. Lucht, J.; Nüchter, A. in Proceedings of Optical 3D Metrology 2019, ISPRS Int. Archieves Photogrammetry and Remote Sensing, Spatial Inf. Sci., XLII-2/W18 (2019). 13–18.
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  This paper presents an underwater laser scanning system and GNSS based trajectory estimation system for scanning from a surface vessle in shallow water. The system has an above-the-water and an underwater component. Above-the-water two low-cost multi- band GNSS receivers with an antenna baseline of one meter are used for RTK positioning with heading. The full 6-DOF is estimated by fusing the satellite navigation data with a MEMS-based INS. The 3D data is captured in water using a structured light scanner consisting of a low-light underwater camera and a green cross line laser projector. We describe the development of the system and employed hardware components. We show results of scanning a large test object in a water tank acquired by from a tripod with a motorized yaw axis. Additionally, we demonstrate first results of mobile mapping from a floating platform. We evaluate the performance of the system by measuring the 6-DOF trajectory with an external optical tracking system. Additionally, we assess the quality of the created point cloud using reference objects placed in the scene.

  @inproceedings{O3DM2019, abstract = {This paper presents an underwater laser scanning system and GNSS based trajectory estimation system for scanning from a surface vessle in shallow water. The system has an above-the-water and an underwater component. Above-the-water two low-cost multi- band GNSS receivers with an antenna baseline of one meter are used for RTK positioning with heading. The full 6-DOF is estimated by fusing the satellite navigation data with a MEMS-based INS. The 3D data is captured in water using a structured light scanner consisting of a low-light underwater camera and a green cross line laser projector. We describe the development of the system and employed hardware components. We show results of scanning a large test object in a water tank acquired by from a tripod with a motorized yaw axis. Additionally, we demonstrate first results of mobile mapping from a floating platform. We evaluate the performance of the system by measuring the 6-DOF trajectory with an external optical tracking system. Additionally, we assess the quality of the created point cloud using reference objects placed in the scene.}, address = {Strasbourg, France}, author = {Bleier, M. and v.d. Lucht, J. and N{\"u}chter, A.}, booktitle = {Proceedings of Optical 3D Metrology 2019}, keywords = {myown}, month = {November}, pages = {13–18}, series = {ISPRS Int. Archieves Photogrammetry and Remote Sensing, Spatial Inf. Sci., XLII-2/W18}, title = {SCOUT3D – An underwater laser scanning system for mobile mapping}, year = 2019 }
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  Self-calibrated Surface Acquisition for Integrated Positioning Verification in Medical Applications Jörissen, S.; Bleier, M.; Nüchter, A. in Proceedings of the IS\&T International Symposium on Electronic Imaging Science and Technology, Electronic Imaging (2019). 353–1.
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  This paper presents a novel approach for a position verification system in medical applications. By replacing the already existing cross line laser projectors with galvo- or MEMS-based projectors and utilizing the surveillance cameras, a self-calibration of the system is performed and surface acquisition for positioning verification is demonstrated. The functionality is shown by analyzing the radii of calibration spheres and determining the quality of the captured surface with respect to a reference model. The paper focuses on the demonstration with one pair of camera and projector but can also be extended to a multi-camera-projector system, as present in treatment rooms. Compared to other systems, this approach does not need external hardware and is thus space and cost efficient.

  @inproceedings{EI2019, abstract = {This paper presents a novel approach for a position verification system in medical applications. By replacing the already existing cross line laser projectors with galvo- or MEMS-based projectors and utilizing the surveillance cameras, a self-calibration of the system is performed and surface acquisition for positioning verification is demonstrated. The functionality is shown by analyzing the radii of calibration spheres and determining the quality of the captured surface with respect to a reference model. The paper focuses on the demonstration with one pair of camera and projector but can also be extended to a multi-camera-projector system, as present in treatment rooms. Compared to other systems, this approach does not need external hardware and is thus space and cost efficient.}, address = {San Francisco, CA, USA}, author = {J{\"o}rissen, S. and Bleier, M. and N{\"u}chter, A.}, booktitle = {Proceedings of the IS\&T International Symposium on Electronic Imaging Science and Technology}, keywords = {myown}, month = {January}, pages = {353-1–353-8}, publisher = {Society for Imaging Science and Technology}, series = {Electronic Imaging}, title = {{Self-calibrated Surface Acquisition for Integrated Positioning Verification in Medical Applications}}, year = 2019 }
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  Signed Distance Based Reconstruction for Exploration and Change Detection in Underground Mining Disaster Prevention Koch, P.; May, S.; Engelhardt, H.; Ziegler, J.; Nüchter, A. in IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’19) (2019). 1–2.
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  This publication describes an application of a Truncated Signed Distance Mapping approach for disaster intervention in underground mine shafts through geometrical change detection of the shaft walls. The paper describes two main problems of such an approach (aligning two potentially huge point clouds and automatic change detection by comparing the reconstructed volumes) and explains in detail the proposed solution.

  @inproceedings{SSRR2019_3, abstract = {This publication describes an application of a Truncated Signed Distance Mapping approach for disaster intervention in underground mine shafts through geometrical change detection of the shaft walls. The paper describes two main problems of such an approach (aligning two potentially huge point clouds and automatic change detection by comparing the reconstructed volumes) and explains in detail the proposed solution.}, author = {{Koch}, P. and {May}, S. and {Engelhardt}, H. and {Ziegler}, J. and {N{\"u}chter}, A.}, booktitle = {IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '19)}, keywords = {myown}, month = {September}, pages = {1–2}, title = {{Signed Distance Based Reconstruction for Exploration and Change Detection in Underground Mining Disaster Prevention}}, year = 2019 }
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  Technical Report: Reduction and Compression using Octrees --- 3DTK’s entry to the ICIP 2019 Challenge on Point Cloud Coding Nüchter, A.; Schauer, J.; Borrmann, D. (2019).
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  Modern photogrammetric methods as well as laser measurement systems make it easy to collect large 3D point clouds that sample objects or environments. Several mechanisms are available in literature for storing and compressing point clouds, e.g., applying conventional image based compression methods to 3D point clouds. In this challenge entry however, we make use of octree subsampling and compression, which is nicely suited for unstructured, registered 3D point clouds of arbitrarily shaped objects.

  @techreport{ICIP2019, abstract = {Modern photogrammetric methods as well as laser measurement systems make it easy to collect large 3D point clouds that sample objects or environments. Several mechanisms are available in literature for storing and compressing point clouds, e.g., applying conventional image based compression methods to 3D point clouds. In this challenge entry however, we make use of octree subsampling and compression, which is nicely suited for unstructured, registered 3D point clouds of arbitrarily shaped objects.}, address = {Würzburg, Germany}, author = {N{\"u}chter, A. and Schauer, J. and Borrmann, D.}, institution = {Robotics and Telematics, University of Würzburg}, keywords = {myown}, month = {September}, title = {{Technical Report: Reduction and Compression using Octrees — {3DTK}'s entry to the {ICIP} 2019 Challenge on Point Cloud Coding}}, year = 2019 }
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  The Eins3D Project -- Instantaneous UAV-Based 3D Mapping for Search and Rescue Applications Lauterbach, H. A.; Koch, C. B.; Hess, R.; Eck, D.; Schilling, K.; Nüchter, A. in IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’19) (2019). 1–6.
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  The overview of a situation in a search and rescue disaster is the key aspect of an effective assistance. In the recent years the utilization of multicopter with various photogrammetry systems is an upcoming trend and an open field of research. This paper discusses the technical aspects of an automated integral system that will support rescuers during the strategic mission planning and will give situational awareness by instantaneous 3D mapping. The approach combines sensors including a 3D Laserscanner, a thermal camera and an attitude system as a payload unit on an Multicopter. The continuous data fusion and the down link are providing an instant 3D environment map that is continuously revised and updated.

  @inproceedings{SSRR2019_1, abstract = {The overview of a situation in a search and rescue disaster is the key aspect of an effective assistance. In the recent years the utilization of multicopter with various photogrammetry systems is an upcoming trend and an open field of research. This paper discusses the technical aspects of an automated integral system that will support rescuers during the strategic mission planning and will give situational awareness by instantaneous 3D mapping. The approach combines sensors including a 3D Laserscanner, a thermal camera and an attitude system as a payload unit on an Multicopter. The continuous data fusion and the down link are providing an instant 3D environment map that is continuously revised and updated.}, author = {{Lauterbach}, H. A. and {Koch}, C. B. and {Hess}, R. and {Eck}, D. and {Schilling}, K. and {N{\"u}chter}, A.}, booktitle = {IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '19)}, keywords = {myown}, month = {September}, pages = {1–6}, title = {{The Eins3D Project – Instantaneous UAV-Based 3D Mapping for Search and Rescue Applications}}, year = 2019 }
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  The Golden Bullet: A Comparative Study for Target Acquisition, Pointing and Shooting Heydn, K. A. M.; Dietrich, M. P.; Barkowsky, M.; Winterfeldt, G.; von Mammen, S.; Nüchter, A. in 11th International Conference on Virtual Worlds and Games for Serious Applications (VS-Games ’19) (2019). 1–8.
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  In this study, we evaluate an interaction sequence performed by six modalities consisting of desktop-based (DB) and virtual reality (VR) environments using different input devices. For the given study, we implemented a vertical prototype of a first person shooter (FPS) game scenario, focusing on the genre-defining point-and-shoot mechanic. We introduce measures to evaluate the success of the according interaction sequence (times for target acquisition, pointing, shooting, overall net time, and number of shots) and conduct experiments to record and compare the users' performances. We show that interacting using head-tracking for landscape-rotation is performing similarly to the input of a screen-centered mouse and also yielded shortest times in target acquisition and pointing. Although using head-tracking for target acquisition and pointing was most efficient, subjects rated the modality using head-tracking for target acquisition and a 3DOF Controller for pointing best. Eye-tracking (ET) yields promising results, but calibration issues need to be resolved to enhance reliability and overall user experience.

  @inproceedings{VSGAMES2019, abstract = {In this study, we evaluate an interaction sequence performed by six modalities consisting of desktop-based (DB) and virtual reality (VR) environments using different input devices. For the given study, we implemented a vertical prototype of a first person shooter (FPS) game scenario, focusing on the genre-defining point-and-shoot mechanic. We introduce measures to evaluate the success of the according interaction sequence (times for target acquisition, pointing, shooting, overall net time, and number of shots) and conduct experiments to record and compare the users' performances. We show that interacting using head-tracking for landscape-rotation is performing similarly to the input of a screen-centered mouse and also yielded shortest times in target acquisition and pointing. Although using head-tracking for target acquisition and pointing was most efficient, subjects rated the modality using head-tracking for target acquisition and a 3DOF Controller for pointing best. Eye-tracking (ET) yields promising results, but calibration issues need to be resolved to enhance reliability and overall user experience.}, author = {{Heydn}, K. A. M. and {Dietrich}, M. P. and {Barkowsky}, M. and {Winterfeldt}, G. and {von Mammen}, S. and {N{\"u}chter}, A.}, booktitle = {11th International Conference on Virtual Worlds and Games for Serious Applications (VS-Games '19)}, keywords = {imported}, month = {September}, pages = {1–8}, title = {The Golden Bullet: A Comparative Study for Target Acquisition, Pointing and Shooting}, year = 2019 }
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  Towards an Underwater 3D Laser Scanning System for Mobile Mapping Bleier, M.; van der Lucht, J.; Nüchter, A. in Proceedings of the IEEE ICRA Workshop on Underwater Robotic Perception (ICRAURP ’19) (2019).
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  Digitizing archaeological or industrial sites on land using standard methods of photogrammetry like 3D modeling from photos or laser scanning is well understood. In contrast, precise underwater surveying with high resolution is still a complex and difficult task. In this paper, we present the development and construction of a structured light underwater laser scanning system and show first results on applying the system for mobile scanning in the water. The laser scanner employs two line lasers to project a cross on the scene. This enables mobile scanning in multiple directions and provides an overlapping scan pattern, which is exploited for trajectory optimization. We describe the image processing, calibration and 3D reconstruction methods used for creating point clouds using the system. In experiments conducted in a towing tank we demonstrate 3D scans captured by rotating the scanner on a robotic joint and first results of mobile scans acquired by moving the scanner through the water along a linear trajectory.

  @inproceedings{ICRAURP2019, abstract = {Digitizing archaeological or industrial sites on land using standard methods of photogrammetry like 3D modeling from photos or laser scanning is well understood. In contrast, precise underwater surveying with high resolution is still a complex and difficult task. In this paper, we present the development and construction of a structured light underwater laser scanning system and show first results on applying the system for mobile scanning in the water. The laser scanner employs two line lasers to project a cross on the scene. This enables mobile scanning in multiple directions and provides an overlapping scan pattern, which is exploited for trajectory optimization. We describe the image processing, calibration and 3D reconstruction methods used for creating point clouds using the system. In experiments conducted in a towing tank we demonstrate 3D scans captured by rotating the scanner on a robotic joint and first results of mobile scans acquired by moving the scanner through the water along a linear trajectory.}, address = {Montreal, Canada}, author = {Bleier, M. and van der Lucht, J. and N{\"u}chter, A.}, booktitle = {Proceedings of the IEEE ICRA Workshop on Underwater Robotic Perception (ICRAURP '19)}, keywords = {author}, month = {may}, title = {Towards an Underwater 3D Laser Scanning System for Mobile Mapping}, year = 2019 }

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  Augmented field Geology and Geophysics for Planetary Analogues (Poster) Rossi, A. Pio; Unnithan, V.; Torrese, P.; Borrmann, D.; Nüchter, A.; Lauterbach, H.; Ortenzi, G.; Jährig, T.; Sohl, F. in Proceedings of the EGU General Assembly 2018, Pico session: Planetary geobiological analogs for Mars and beyond: Field, lab and simulations (2018). (Vol. 20)
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  @inproceedings{EGU2018, address = {Vienna, Austria}, author = {Rossi, A. Pio and Unnithan, V. and Torrese, P. and Borrmann, D. and N{\"u}chter, A. and Lauterbach, H. and Ortenzi, G. and J{\"a}hrig, T. and Sohl, F.}, booktitle = {Proceedings of the EGU General Assembly 2018, Pico session: Planetary geobiological analogs for Mars and beyond: Field, lab and simulations}, keywords = {imported}, month = {April}, number = {EGU2018-6389}, title = {{Augmented field Geology and Geophysics for Planetary Analogues (Poster)}}, volume = 20, year = 2018 }
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  Benchmarking Structure from Motion Algorithms of Urban Environments with Applications to Reconnaissance in Search and Rescue Scenarios Martell, A.; Lauterbach, H. A.; Schilling, K.; Nüchter, A. in Proceedings of the 16th IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’18) (2018). 1–7.
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  @inproceedings{8468612, address = {Philadelphia, PA, USA}, author = {Martell, A. and Lauterbach, H. A. and Schilling, K. and N{\"u}chter, A.}, booktitle = {Proceedings of the 16th IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '18)}, keywords = {imported}, month = {August}, pages = {1–7}, title = {{Benchmarking Structure from Motion Algorithms of Urban Environments with Applications to Reconnaissance in Search and Rescue Scenarios}}, year = 2018 }
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  Body Weight Estimation for Dose-Finding and Health Monitoring of Lying, Standing and Walking Patients Based on RGB-D Data Pfitzner, C.; May, S.; Nüchter, A. in Sensors (2018). 18(5)
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  This paper describes the estimation of the body weight of a person in front of an RGB-D camera. A survey of different methods for body weight estimation based on depth sensors is given. First, an estimation of people standing in front of a camera is presented. Second, an approach based on a stream of depth images is used to obtain the body weight of a person walking towards a sensor. The algorithm first extracts features from a point cloud and forwards them to an artificial neural network (ANN) to obtain an estimation of body weight. Besides the algorithm for the estimation, this paper further presents an open-access dataset based on measurements from a trauma room in a hospital as well as data from visitors of a public event. In total, the dataset contains 439 measurements. The article illustrates the efficiency of the approach with experiments with persons lying down in a hospital, standing persons, and walking persons. Applicable scenarios for the presented algorithm are body weight-related dosing of emergency patients.

  @article{SENSORS2018, abstract = {This paper describes the estimation of the body weight of a person in front of an RGB-D camera. A survey of different methods for body weight estimation based on depth sensors is given. First, an estimation of people standing in front of a camera is presented. Second, an approach based on a stream of depth images is used to obtain the body weight of a person walking towards a sensor. The algorithm first extracts features from a point cloud and forwards them to an artificial neural network (ANN) to obtain an estimation of body weight. Besides the algorithm for the estimation, this paper further presents an open-access dataset based on measurements from a trauma room in a hospital as well as data from visitors of a public event. In total, the dataset contains 439 measurements. The article illustrates the efficiency of the approach with experiments with persons lying down in a hospital, standing persons, and walking persons. Applicable scenarios for the presented algorithm are body weight-related dosing of emergency patients.}, author = {Pfitzner, C. and May, S. and N{\"u}chter, A.}, journal = {Sensors}, keywords = {imported}, month = {April}, number = 5, title = {Body Weight Estimation for Dose-Finding and Health Monitoring of Lying, Standing and Walking Patients Based on RGB-D Data}, volume = 18, year = 2018 }
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  Continuous-Time SLAM --- Improving Google’s Cartographer 3D Mapping Nüchter, A.; Bleier, M.; Schauer, J.; Janotta, P. in Latest Developments in Reality-Based 3D Surveying and Modelling, F. Remondino, A. Georgopoulos, D. Gonzalez-Aguilera, P. Agrafiotis (eds.) (2018). 53–73.
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  This paper shows how to use the result of Google’s simultaneous localization and mapping (SLAM) solution, called Cartographer, to bootstrap a continuous-time SLAM algorithm that was developed by the authors and presented in previous publications. The presented approach optimizes the consistency of the global point cloud, and thus improves on Google’s results. Algorithms and data from Google are used as input for the continuous-time SLAM software. In preceding work, the continuous-time SLAM was successfully applied to a similar backpack system which delivers consistent 3D point clouds even in the absence of an IMU. Continuous-time SLAM means that the trajectory of a mobile mapping system is treated in a semi-rigid fashion, i.e., the trajectory is deformed to yield a consistent 3D point cloud of the measured environment.

  @incollection{MDPI2018, abstract = {This paper shows how to use the result of Google’s simultaneous localization and mapping (SLAM) solution, called Cartographer, to bootstrap a continuous-time SLAM algorithm that was developed by the authors and presented in previous publications. The presented approach optimizes the consistency of the global point cloud, and thus improves on Google’s results. Algorithms and data from Google are used as input for the continuous-time SLAM software. In preceding work, the continuous-time SLAM was successfully applied to a similar backpack system which delivers consistent 3D point clouds even in the absence of an IMU. Continuous-time SLAM means that the trajectory of a mobile mapping system is treated in a semi-rigid fashion, i.e., the trajectory is deformed to yield a consistent 3D point cloud of the measured environment.}, address = {Basel, Switzerland}, author = {N{\"u}chter, A. and Bleier, M. and Schauer, J. and Janotta, P.}, booktitle = {Latest Developments in Reality-Based 3D Surveying and Modelling}, chapter = {Continuous-Time SLAM — Improving Google’s Cartographer 3D Mapping}, editor = {Remondino, F. and Georgopoulos, A. and Gonzalez-Aguilera, D. and Agrafiotis, P.}, keywords = {myown}, month = {January}, pages = {53–73}, publisher = {MDPI}, title = {Continuous-Time SLAM — Improving Google’s Cartographer 3D Mapping}, year = 2018 }
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  Korrektur der Brechung an der Wasseroberfläche beim triangulationsbasierten 3D-Laserscannen van der Lucht, J.; Bleier, M.; Leutert, F.; Schilling, K.; Nüchter, A. in Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beiträge der Oldenburger 3D-Tage 2018, Jade Hochschule (2018). 87–102.
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  Die vorliegende Arbeit beschäftigt sich mit der Korrektur der Brechung an der Wasseroberfläche beim triangulationsbasierten 3D Laserscannen. Hierzu wurde eine Methode entwickelt, die es ermöglicht, mit einem Structured Light (SL) System 3D-Daten von teilweise mit Wasser bedeckten Strukturen anzufertigen und die dabei entstehende Brechung an der Wasseroberfläche zu korrigieren. Diese wurde anschließend in einem Versuchsaufbau evaluiert. Der Scanner wurde dabei an einem KUKA KR-16 Manipulatorarm befestigt, was die Möglichkeit bietet den Scanner gleichmäßig, definiert und wiederholbar zu bewegen. Die Bewegungen des Scanners wurden dabei durch ein externes Trackingsystem erfasst. Ebenfalls wurde bei diesen Versuchen der Einfluss verschiedener Einstrahlwinkel betrachtet. Zu diesem Zweck wurde der Scanner in verschiedenen Winkeln relativ zur Wasseroberfläche bewegt. Durch die entwickelte Methode konnten Fehler durch die Brechung an der Wasseroberfläche erfolgreich korrigiert werden. Außerdem konnte die Lage der Wasseroberfläche ohne externe Markierungen aus den 3D-Daten bestimmt werden.

  @inproceedings{3DTAGE2018, abstract = {Die vorliegende Arbeit beschäftigt sich mit der Korrektur der Brechung an der Wasseroberfläche beim triangulationsbasierten 3D Laserscannen. Hierzu wurde eine Methode entwickelt, die es ermöglicht, mit einem Structured Light (SL) System 3D-Daten von teilweise mit Wasser bedeckten Strukturen anzufertigen und die dabei entstehende Brechung an der Wasseroberfläche zu korrigieren. Diese wurde anschließend in einem Versuchsaufbau evaluiert. Der Scanner wurde dabei an einem KUKA KR-16 Manipulatorarm befestigt, was die Möglichkeit bietet den Scanner gleichmäßig, definiert und wiederholbar zu bewegen. Die Bewegungen des Scanners wurden dabei durch ein externes Trackingsystem erfasst. Ebenfalls wurde bei diesen Versuchen der Einfluss verschiedener Einstrahlwinkel betrachtet. Zu diesem Zweck wurde der Scanner in verschiedenen Winkeln relativ zur Wasseroberfläche bewegt. Durch die entwickelte Methode konnten Fehler durch die Brechung an der Wasseroberfläche erfolgreich korrigiert werden. Außerdem konnte die Lage der Wasseroberfläche ohne externe Markierungen aus den 3D-Daten bestimmt werden.}, author = {van der Lucht, J. and Bleier, M. and Leutert, F. and Schilling, K. and N{\"u}chter, A.}, booktitle = {Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beitr{\"a}ge der Oldenburger 3D-Tage 2018, Jade Hochschule}, keywords = {imported}, month = {February}, pages = {87–102}, title = {{Korrektur der Brechung an der Wasseroberfl{\"a}che beim triangulationsbasierten 3D-Laserscannen}}, year = 2018 }
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  Positioning. Navigation and Awareness of the !VAMOS! Underwater Robotic Mining System Almeida, J.; Martins, A.; Almeida, C.; Dias, A.; Matias, B.; Ferreira, A.; Jorge, P.; Martins, R.; Bleier, M.; Nüchter, A.; Pidgeon, J.; Kapusniak, S.; Silva, E. in IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS ’18) (2018). 1527–1533.
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  This paper presents the positioning, navigation and awareness (PNA) system developed for the Underwater Robotic Mining System of the !VAMOS! project [1]. It describes the main components of the !VAMOS! system, the PNA sensors in each of those components, the global architecture of the PNA system, and its main subsystems: Position and Navigation, Realtime Mine Modeling, 3D Virtual reality HMI and Real-time grade system. General results and lessons learn during the first mining field trial in Lee Moor, Devon, UK during the months of September and October 2017 are presented.

  @inproceedings{IROS2018, abstract = {This paper presents the positioning, navigation and awareness (PNA) system developed for the Underwater Robotic Mining System of the !VAMOS! project [1]. It describes the main components of the !VAMOS! system, the PNA sensors in each of those components, the global architecture of the PNA system, and its main subsystems: Position and Navigation, Realtime Mine Modeling, 3D Virtual reality HMI and Real-time grade system. General results and lessons learn during the first mining field trial in Lee Moor, Devon, UK during the months of September and October 2017 are presented.}, author = {Almeida, J. and Martins, A. and Almeida, C. and Dias, A. and Matias, B. and Ferreira, A. and Jorge, P. and Martins, R. and Bleier, M. and N{\"u}chter, A. and Pidgeon, J. and Kapusniak, S. and Silva, E.}, booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS '18)}, keywords = {imported}, pages = {1527–1533}, title = {{Positioning. Navigation and Awareness of the !VAMOS! Underwater Robotic Mining System}}, year = 2018 }
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  Preliminary Results on Instantaneous UAV-Based 3D Mapping for Rescue Applications Lauterbach, H. A.; Nüchter, A. in Proceedings of the 16th IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR ’18) (2018). 1–2.
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  This report presents a novel approach to generate a 3D map with an UAV while flying over a disaster scene with the aim to present the map instantaneously to the operator and the rescue workers. Our approach extends the well-known ICP algorithm.

  @inproceedings{lauterbach2018preliminary, abstract = {This report presents a novel approach to generate a 3D map with an UAV while flying over a disaster scene with the aim to present the map instantaneously to the operator and the rescue workers. Our approach extends the well-known ICP algorithm.}, address = {Philadelphia, PA, USA}, author = {Lauterbach, H. A. and N{\"u}chter, A.}, booktitle = {Proceedings of the 16th IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR '18)}, keywords = {imported}, month = {August}, pages = {1–2}, title = {{Preliminary Results on Instantaneous UAV-Based 3D Mapping for Rescue Applications}}, year = 2018 }
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  RADLER - A RADial LasER scanning device Borrmann, D.; Jörissen, S.; Nüchter, A. in Proceedings of the 16th International Symposium of Experimental Robotics (ISER ’18), Springer Tracts in Advanced Robotics (2018). 655–664.
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  Mobile scanning, i.e., the practice of mounting laser scanners on moving platforms is an efficient way to acquire accurate and dense 3D point clouds of outdoor environments for urban and regional planning and architecture. The mobile scenario puts high requirements on the accuracy of the calibration of the measurement system, as small calibration inaccuracies lead to large errors in the resulting point cloud. We propose a novel algorithm for the calibration of a mobile scanning system that estimates the calibration parameters for all sensor components simultaneously without relying on additional hardware. We evaluate the calibration algorithm on several real world data sets where ground truth is available via an accurate geodetic model.

  @inproceedings{ISER2018, abstract = {Mobile scanning, i.e., the practice of mounting laser scanners on moving platforms is an efficient way to acquire accurate and dense 3D point clouds of outdoor environments for urban and regional planning and architecture. The mobile scenario puts high requirements on the accuracy of the calibration of the measurement system, as small calibration inaccuracies lead to large errors in the resulting point cloud. We propose a novel algorithm for the calibration of a mobile scanning system that estimates the calibration parameters for all sensor components simultaneously without relying on additional hardware. We evaluate the calibration algorithm on several real world data sets where ground truth is available via an accurate geodetic model.}, address = {Buenos Aires, Argentina}, author = {Borrmann, D. and J{\"o}rissen, S. and N{\"u}chter, A.}, booktitle = {Proceedings of the 16th International Symposium of Experimental Robotics (ISER '18)}, keywords = {imported}, month = {November}, pages = {655-664}, series = {Springer Tracts in Advanced Robotics}, title = {{RADLER - A RADial LasER scanning device}}, year = 2018 }
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  Reconstructing the subsurface of planetary volcanic analogues: ERT imaging of Lanzarote lava tubes complemented with drone stereogrammetry, surface and in-cave LiDAR and seismic investigations (Poster) Torrese, P.; Rossi, A. Pio; Unnithan, V.; Borrmann, D.; Lauterbach, H.; Ortenzi, G.; Jährig, T.; Pozzobon, R.; Sauro, F.; Santagata, T.; Nüchter, A.; Sohl, F. in Proceedings of the EGU General Assembly 2018, Pico session: Planetary geobiological analogs for Mars and beyond: Field, lab and simulations (2018). (Vol. 20)
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  @inproceedings{EGU2018, address = {Vienna, Austria}, author = {Torrese, P. and Rossi, A. Pio and Unnithan, V. and Borrmann, D. and Lauterbach, H. and Ortenzi, G. and J{\"a}hrig, T. and Pozzobon, R. and Sauro, F. and Santagata, T. and N{\"u}chter, A. and Sohl, F.}, booktitle = {Proceedings of the EGU General Assembly 2018, Pico session: Planetary geobiological analogs for Mars and beyond: Field, lab and simulations}, keywords = {imported}, month = {April}, number = {EGU2018-14285}, title = {{Reconstructing the subsurface of planetary volcanic analogues: ERT imaging of Lanzarote lava tubes complemented with drone stereogrammetry, surface and in-cave LiDAR and seismic investigations (Poster)}}, volume = 20, year = 2018 }
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  Removing non-static objects from 3D laser scan data Schauer, Johannes; Nüchter, Andreas in ISPRS Journal of Photogrammetry and Remote Sensing (JPRS) (2018). 143 15–38.
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  For the purpose of visualization and further post-processing of 3D point cloud data, it is often desirable to remove moving objects from a given data set. Common examples for these moving objects are pedestrians, bicycles and motor vehicles in outdoor scans or manufactured goods and employees in indoor scans of factories. We present a new change detection method which is able to partition the points of multiple registered 3D scans into two sets: points belonging to stationary (static) objects and points belonging to moving (dynamic) objects. Our approach does not require any object detection or tracking the movement of objects over time. Instead, we traverse a voxel grid to find differences in volumetric occupancy for “explicit” change detection. Our main contribution is the introduction of the concept of “point shadows” and how to efficiently compute them. Without them, using voxel grids for explicit change detection is known to suffer from a high number of false positives when applied to terrestrial scan data. Our solution achieves similar quantitative results in terms of F1-score as competing methods while at the same time being faster.

  @article{JPRS_2018, abstract = {For the purpose of visualization and further post-processing of 3D point cloud data, it is often desirable to remove moving objects from a given data set. Common examples for these moving objects are pedestrians, bicycles and motor vehicles in outdoor scans or manufactured goods and employees in indoor scans of factories. We present a new change detection method which is able to partition the points of multiple registered 3D scans into two sets: points belonging to stationary (static) objects and points belonging to moving (dynamic) objects. Our approach does not require any object detection or tracking the movement of objects over time. Instead, we traverse a voxel grid to find differences in volumetric occupancy for “explicit” change detection. Our main contribution is the introduction of the concept of “point shadows” and how to efficiently compute them. Without them, using voxel grids for explicit change detection is known to suffer from a high number of false positives when applied to terrestrial scan data. Our solution achieves similar quantitative results in terms of F1-score as competing methods while at the same time being faster.}, author = {Schauer, Johannes and N{\"u}chter, Andreas}, journal = {ISPRS Journal of Photogrammetry and Remote Sensing (JPRS)}, keywords = {imported}, pages = {15–38}, title = {Removing non-static objects from 3D laser scan data}, volume = 143, year = 2018 }
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  Structured-light based 3D laser scanning of semi-submerged structures van der Lucht, J.; Bleier, M.; Leutert, F.; Schilling, K.; Nüchter, A. in Proceedings of the Technical Commision II Mid-term Symposium ``Towards Photogrammetry 2020’’, ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., IV-2 (2018). 287–294.
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  In this work we look at 3D acquisition of semi-submerged structures with a triangulation based underwater laser scanning system. The motivation is that we want to simultaneously capture data above and below water to create a consistent model without any gaps. The employed structured light scanner consist of a machine vision camera and a green line laser. In order to reconstruct precise surface models of the object it is necessary to model and correct for the refraction of the laser line and camera rays at the water-air boundary. We derive a geometric model for the refraction at the air-water interface and propose a method for correcting the scans. Furthermore, we show how the water surface is directly estimated from sensor data. The approach is verified using scans captured with an industrial manipulator to achieve reproducable scanner trajectories with different incident angles. We show that the proposed method is effective for refractive correction and that it can be applied directly to the raw sensor data without requiring any external markers or targets.

  @inproceedings{COMMII2018, abstract = {In this work we look at 3D acquisition of semi-submerged structures with a triangulation based underwater laser scanning system. The motivation is that we want to simultaneously capture data above and below water to create a consistent model without any gaps. The employed structured light scanner consist of a machine vision camera and a green line laser. In order to reconstruct precise surface models of the object it is necessary to model and correct for the refraction of the laser line and camera rays at the water-air boundary. We derive a geometric model for the refraction at the air-water interface and propose a method for correcting the scans. Furthermore, we show how the water surface is directly estimated from sensor data. The approach is verified using scans captured with an industrial manipulator to achieve reproducable scanner trajectories with different incident angles. We show that the proposed method is effective for refractive correction and that it can be applied directly to the raw sensor data without requiring any external markers or targets.}, address = {Riva del Garda, Italy}, author = {van der Lucht, J. and Bleier, M. and Leutert, F. and Schilling, K. and N{\"u}chter, A.}, booktitle = {Proceedings of the Technical Commision II Mid-term Symposium ``Towards Photogrammetry 2020''}, keywords = {imported}, month = {June}, pages = {287–294}, series = {ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., IV-2}, title = {{Structured-light based 3D laser scanning of semi-submerged structures}}, year = 2018 }
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  The Peopleremover --- Removing Dynamic Objects From 3-D Point Cloud Data by Traversing a Voxel Occupancy Grid Schauer, J.; Nüchter, A. in IEEE Robotics and Automation Letters (RAL) (2018). 3(3) 1679–1686.
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  Even though it would be desirable for most postprocessing purposes to obtain a point cloud without moving objects in it, it is often impractical or downright impossible to free a scene from all nonstatic clutter. Outdoor environments contain pedestrians, bicycles, and motor vehicles which cannot easily be stopped from entering the sensor range and indoor environments like factory production lines cannot be evacuated due to production losses during the time of the scan. In this letter, we present a solution to this problem that we call the "peopleremover." Given a registered set of 3-D point clouds, we build a regular voxel occupancy grid and then traverse it along the lines of sight between the sensor and the measured points to find the differences in volumetric occupancy between the scans. Our approach works for scan slices from mobile mapping as well as for the more general scenario of terrestrial scan data. The result is a clean point cloud free of dynamic objects.

  @article{ICRA2018, abstract = {Even though it would be desirable for most postprocessing purposes to obtain a point cloud without moving objects in it, it is often impractical or downright impossible to free a scene from all nonstatic clutter. Outdoor environments contain pedestrians, bicycles, and motor vehicles which cannot easily be stopped from entering the sensor range and indoor environments like factory production lines cannot be evacuated due to production losses during the time of the scan. In this letter, we present a solution to this problem that we call the "peopleremover." Given a registered set of 3-D point clouds, we build a regular voxel occupancy grid and then traverse it along the lines of sight between the sensor and the measured points to find the differences in volumetric occupancy between the scans. Our approach works for scan slices from mobile mapping as well as for the more general scenario of terrestrial scan data. The result is a clean point cloud free of dynamic objects.}, author = {Schauer, J. and N{\"u}chter, A.}, journal = {IEEE Robotics and Automation Letters (RAL)}, keywords = {imported}, month = {July}, number = 3, pages = {1679–1686}, title = {{{The Peopleremover — Removing Dynamic Objects From 3-D Point Cloud Data by Traversing a Voxel Occupancy Grid}}}, volume = 3, year = 2018 }
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  TOM: A formation for photogrammetric earth observation by three cubesats Schilling, K.; Tzschichholz, T.; Motroniuk, I.; Aumann, A.; Mammadov, I.; Ruf, O.; Schmidt, C.; Appel, N.; Kleinschrodt, A.; Montenegro, S.; Nüchter, A. in Proceedings IAA-ASS-17 : International Academy of Astronautics, Advances in the Astronautical Sciences 4th IAA Dynamics and Control of Space Systems Conference (2018). (Vol. 163) 1–14.
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  @inproceedings{IAA2017, address = {Rome, Italy}, author = {Schilling, K. and Tzschichholz, T. and Motroniuk, I. and Aumann, A. and Mammadov, I. and Ruf, O. and Schmidt, C. and Appel, N. and Kleinschrodt, A. and Montenegro, S. and N{\"u}chter, A.}, booktitle = {Proceedings IAA-ASS-17 : International Academy of Astronautics}, keywords = {imported}, month = {may}, number = {IAA-AAS-CU-17-08-02}, pages = {1–14}, publisher = {Univelt, Inc.}, series = {Advances in the Astronautical Sciences 4th IAA Dynamics and Control of Space Systems Conference}, title = {TOM: A formation for photogrammetric earth observation by three cubesats}, volume = 163, year = 2018 }
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  Workshop: Large-Scale 3D Point Cloud Processing for Mixed and Augmented Reality Borrmann, D.; Nüchter, A.; Wiemann, T. in IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct ’08) (2018). xxxv.
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  The rapid development of 3D scanning technology combined with state-of-the-art mapping algorithms allows to capture 3D point clouds with high resolution and accuracy. The high amount of data collected with LiDAR, RGB-D cameras or generated through SfM approaches makes the direct use of the recorded data for realistic rendering and simulation problematic. Therefore, these point clouds have to be transformed into representations that fulfill the computational requirements for VR and AR setups. In this tutorial participants will be introduced to state-of-the-art methods in point cloud processing and surface reconstruction with open source software to learn the benefits for AR and VR applications by interleaved presentations, software demonstrations and software trials. The focus lies on 3D point cloud data structures (range images, octrees, k-d trees) and algorithms, and their implementation in C/C++. Surface reconstruction using Marching Cubes and other meshing methods will play another central role. Reference material for subtopics like 3D point cloud registration and SLAM, calibration, filtering, segmentation, meshing, and large scale surface reconstruction will be provided. Participants are invited to bring their Linux, MacOS or Windows laptops to gain hands-on experience on practical problems occuring when working with large scale 3D point clouds in VR and AR applications.

  @inproceedings{ISMAR2018, abstract = {The rapid development of 3D scanning technology combined with state-of-the-art mapping algorithms allows to capture 3D point clouds with high resolution and accuracy. The high amount of data collected with LiDAR, RGB-D cameras or generated through SfM approaches makes the direct use of the recorded data for realistic rendering and simulation problematic. Therefore, these point clouds have to be transformed into representations that fulfill the computational requirements for VR and AR setups. In this tutorial participants will be introduced to state-of-the-art methods in point cloud processing and surface reconstruction with open source software to learn the benefits for AR and VR applications by interleaved presentations, software demonstrations and software trials. The focus lies on 3D point cloud data structures (range images, octrees, k-d trees) and algorithms, and their implementation in C/C++. Surface reconstruction using Marching Cubes and other meshing methods will play another central role. Reference material for subtopics like 3D point cloud registration and SLAM, calibration, filtering, segmentation, meshing, and large scale surface reconstruction will be provided. Participants are invited to bring their Linux, MacOS or Windows laptops to gain hands-on experience on practical problems occuring when working with large scale 3D point clouds in VR and AR applications.}, author = {{Borrmann}, D. and {N{\"u}chter}, A. and {Wiemann}, T.}, booktitle = {IEEE International Symposium on Mixed and Augmented Reality Adjunct (ISMAR-Adjunct '08)}, keywords = {myown}, month = {October}, pages = {xxxv}, title = {{Workshop: Large-Scale 3D Point Cloud Processing for Mixed and Augmented Reality}}, year = 2018 }

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  Autonomous 3D Modelling of Indoor Spaces Lehtola, V.; Kaartinen, H.; Nüchter, A. in GIM International (2017). 31(10) 20–23.
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  Mobile scanning can be an equally accurate yet more cost-effective solution than traditional terrestrial laser scanning done with tripods. To succeed, however, mobile scanners not only require a suitable combination of sensors, but also reliable and continuous knowledge about where the scanners are located and the direction in which they are pointing during scanning. There are multiple ways to achieve this, which has led to the development of various scientific and commercial solutions. This article compares several mobile scanning solutions for 3D modelling of indoor spaces and highlights their strengths and weaknesses.

  @article{GIM2017, abstract = {Mobile scanning can be an equally accurate yet more cost-effective solution than traditional terrestrial laser scanning done with tripods. To succeed, however, mobile scanners not only require a suitable combination of sensors, but also reliable and continuous knowledge about where the scanners are located and the direction in which they are pointing during scanning. There are multiple ways to achieve this, which has led to the development of various scientific and commercial solutions. This article compares several mobile scanning solutions for 3D modelling of indoor spaces and highlights their strengths and weaknesses.}, author = {Lehtola, V. and Kaartinen, H. and N{\"u}chter, A.}, journal = {GIM International}, keywords = {imported}, month = {October}, number = 10, pages = {20–23}, title = {Autonomous 3D Modelling of Indoor Spaces}, volume = 31, year = 2017 }
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  Chilean underground mine dataset Leung, K. Y. K.; Lühr, D.; Houshiar, H.; Inostroza, F.; Borrmann, D.; Adams, M.; Nüchter, A.; del Solar, J. R. in International Journal of Robotics Research (IJRR) (2017). 36(1) 16–23.
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  This article presents a robotic dataset collected from the largest underground copper mine in the world. The sensor measurements from a 3D scanning lidar, a 2D radar, and stereo cameras were recorded from an approximately two kilometer traverse of a production-active tunnel. The equipment used and the data collection process is discussed in detail, along with the format of the data. This dataset is suitable for research in robotic navigation, as well as simultaneous localization and mapping. The download instructions are available at the following website http://dataset.amtc.cl.

  @article{IJRR2017, abstract = {This article presents a robotic dataset collected from the largest underground copper mine in the world. The sensor measurements from a 3D scanning lidar, a 2D radar, and stereo cameras were recorded from an approximately two kilometer traverse of a production-active tunnel. The equipment used and the data collection process is discussed in detail, along with the format of the data. This dataset is suitable for research in robotic navigation, as well as simultaneous localization and mapping. The download instructions are available at the following website http://dataset.amtc.cl.}, author = {Leung, K. Y. K. and L{\"u}hr, D. and Houshiar, H. and Inostroza, F. and Borrmann, D. and Adams, M. and N{\"u}chter, A. and del Solar, J. R.}, journal = {International Journal of Robotics Research (IJRR)}, keywords = {imported}, month = {January}, number = 1, pages = {16–23}, title = {{Chilean underground mine dataset}}, volume = 36, year = 2017 }
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  Comparison of the Selected State-Of-The-Art 3D Indoor Scanning and Point Cloud Generation Methods Lehtola, V.; Kaartinen, H.; Nüchter, A.; Kaijaluoto, R.; Kukko, A.; Litkey, P.; Honkavaara, E.; Rosnell, T.; Vaaja, M.; Virtanen, J.-P.; et al. in Remote Sensing (2017). 796.
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  Accurate three-dimensional (3D) data from indoor spaces are of high importance for various applications in construction, indoor navigation and real estate management. Mobile scanning techniques are offering an efficient way to produce point clouds, but with a lower accuracy than the traditional terrestrial laser scanning (TLS). In this paper, we first tackle the problem of how the quality of a point cloud should be rigorously evaluated. Previous evaluations typically operate on some point cloud subset, using a manually-given length scale, which would perhaps describe the ranging precision or the properties of the environment. Instead, the metrics that we propose perform the quality evaluation to the full point cloud and over all of the length scales, revealing the method precision along with some possible problems related to the point clouds, such as outliers, over-completeness and misregistration. The proposed methods are used to evaluate the end product point clouds of some of the latest methods. In detail, point clouds are obtained from five commercial indoor mapping systems, Matterport, NavVis, Zebedee, Stencil and Leica Pegasus: Backpack, and three research prototypes, Aalto VILMA, FGI Slammer and the Würzburg backpack. These are compared against survey-grade TLS point clouds captured from three distinct test sites that each have different properties. Based on the presented experimental findings, we discuss the properties of the proposed metrics and the strengths and weaknesses of the above mapping systems and then suggest directions for future research.

  @article{REMSEN2017, abstract = {Accurate three-dimensional (3D) data from indoor spaces are of high importance for various applications in construction, indoor navigation and real estate management. Mobile scanning techniques are offering an efficient way to produce point clouds, but with a lower accuracy than the traditional terrestrial laser scanning (TLS). In this paper, we first tackle the problem of how the quality of a point cloud should be rigorously evaluated. Previous evaluations typically operate on some point cloud subset, using a manually-given length scale, which would perhaps describe the ranging precision or the properties of the environment. Instead, the metrics that we propose perform the quality evaluation to the full point cloud and over all of the length scales, revealing the method precision along with some possible problems related to the point clouds, such as outliers, over-completeness and misregistration. The proposed methods are used to evaluate the end product point clouds of some of the latest methods. In detail, point clouds are obtained from five commercial indoor mapping systems, Matterport, NavVis, Zebedee, Stencil and Leica Pegasus: Backpack, and three research prototypes, Aalto VILMA, FGI Slammer and the Würzburg backpack. These are compared against survey-grade TLS point clouds captured from three distinct test sites that each have different properties. Based on the presented experimental findings, we discuss the properties of the proposed metrics and the strengths and weaknesses of the above mapping systems and then suggest directions for future research.}, author = {Lehtola, V. and Kaartinen, H. and N{\"u}chter, A. and Kaijaluoto, R. and Kukko, A. and Litkey, P. and Honkavaara, E. and Rosnell, T. and Vaaja, M. and Virtanen, J.-P. and et al.}, journal = {Remote Sensing}, keywords = {imported}, month = {August}, pages = 796, title = {{Comparison of the Selected State-Of-The-Art 3D Indoor Scanning and Point Cloud Generation Methods}}, year = 2017 }
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  Detection and Purging of Specular Reflective and Transparent Object Influences in 3D Range Measurements Koch, R.; May, S.; Nüchter, A. in Proceedings of the 7th ISPRS International Workshop 3D-ARCH 2017: "3D Virtual Reconstruction and Visualization of Complex Architectures", ISPRS Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XLII/W3 (2017). 377–384.
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  3D laser scanners are favoured sensors for mapping in mobile service robotics at indoor and outdoor applications, since they deliver precise measurements at a wide scanning range. The resulting maps are detailed since they have a high resolution. Based on these maps robots navigate through rough terrain, fulfil advanced manipulation, and inspection tasks. In case of specular reflective and transparent objects, e.g., mirrors, windows, shiny metals, the laser measurements get corrupted. Based on the type of object and the incident angle of the incoming laser beam there are three results possible: a measurement point on the object plane, a measurement behind the object plane, and a measurement of a reflected object. It is important to detect such situations to be able to handle these corrupted points. This paper describes why it is difficult to distinguish between specular reflective and transparent surfaces. It presents a 3D- Reflection-Pre-Filter Approach to identify specular reflective and transparent objects in point clouds of a multi-echo laser scanner. Furthermore, it filters point clouds from influences of such objects and extract the object properties for further investigations. Based on an Iterative-Closest-Point-algorithm reflective objects are identified. Object surfaces and points behind surfaces are masked according to their location. Finally, the processed point cloud is forwarded to a mapping module. Furthermore, the object surface corners and the type of the surface is broadcasted. Four experiments demonstrate the usability of the 3D-Reflection-Pre-Filter. The first experiment was made in a empty room containing a mirror, the second experiment was made in a stairway containing a glass door, the third experiment was made in a empty room containing two mirrors, the fourth experiment was made in an office room containing a mirror. This paper demonstrate that for single scans the detection of specular reflective and transparent objects in 3D is possible. It is more reliable in 3D as in 2D. Nevertheless, collect the data of multiple scans and post-filter them as soon as the object was bypassed should pursued. This is why future work concentrates on implementing a post-filter module. Besides, it is the aim to improve the discrimination between specular reflective and transparent objects.

  @inproceedings{3DARCH2017_4, abstract = {3D laser scanners are favoured sensors for mapping in mobile service robotics at indoor and outdoor applications, since they deliver precise measurements at a wide scanning range. The resulting maps are detailed since they have a high resolution. Based on these maps robots navigate through rough terrain, fulfil advanced manipulation, and inspection tasks. In case of specular reflective and transparent objects, e.g., mirrors, windows, shiny metals, the laser measurements get corrupted. Based on the type of object and the incident angle of the incoming laser beam there are three results possible: a measurement point on the object plane, a measurement behind the object plane, and a measurement of a reflected object. It is important to detect such situations to be able to handle these corrupted points. This paper describes why it is difficult to distinguish between specular reflective and transparent surfaces. It presents a 3D- Reflection-Pre-Filter Approach to identify specular reflective and transparent objects in point clouds of a multi-echo laser scanner. Furthermore, it filters point clouds from influences of such objects and extract the object properties for further investigations. Based on an Iterative-Closest-Point-algorithm reflective objects are identified. Object surfaces and points behind surfaces are masked according to their location. Finally, the processed point cloud is forwarded to a mapping module. Furthermore, the object surface corners and the type of the surface is broadcasted. Four experiments demonstrate the usability of the 3D-Reflection-Pre-Filter. The first experiment was made in a empty room containing a mirror, the second experiment was made in a stairway containing a glass door, the third experiment was made in a empty room containing two mirrors, the fourth experiment was made in an office room containing a mirror. This paper demonstrate that for single scans the detection of specular reflective and transparent objects in 3D is possible. It is more reliable in 3D as in 2D. Nevertheless, collect the data of multiple scans and post-filter them as soon as the object was bypassed should pursued. This is why future work concentrates on implementing a post-filter module. Besides, it is the aim to improve the discrimination between specular reflective and transparent objects.}, address = {Nafplio, Greece}, author = {Koch, R. and May, S. and N{\"u}chter, A.}, booktitle = {Proceedings of the 7th ISPRS International Workshop 3D-ARCH 2017: "3D Virtual Reconstruction and Visualization of Complex Architectures"}, keywords = {imported}, month = {March}, pages = {377–384}, series = {ISPRS Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XLII/W3}, title = {{Detection and Purging of Specular Reflective and Transparent Object Influences in 3D Range Measurements}}, year = 2017 }
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  Digitizing automotive production lines without interrupting assembly operations through an automatic voxel-based removal of moving objects Schauer, J.; Nüchter, A. in Proceedings of the 13th IEEE International Conference on Control and Automation (ICCA ’17) (2017). 701–706.
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  We present an efficient method to partition a point cloud gathered through kinematic laser scanning into static and dynamic points. The presented algorithm utilizes a voxel grid data structure and uses a ray intersection test to mark voxels as dynamic. The algorithm does not require any ego-motion estimations, computationally expensive object recognition or tracking of moving objects over time. It is easy to implement and can be executed on many cores in parallel. We show the viability of this approach by applying our algorithm to a dataset that we gathered by mounting a FARO Focus3D Laser scanner onto a skid which was then sent along a production line for consumer car chassis in a factory of the Volkswagen corporation. Since factory operators are interested in acquiring digital models of their production lines without suspending factory operations, the resulting point cloud will contain many dynamic objects like humans or other car bodies. We show how our algorithm is able to successfully remove these dynamic objects from the resulting point cloud with minimal errors. Our implementation is published under a free license as part of 3DTK.

  @inproceedings{ICCA2017, abstract = {We present an efficient method to partition a point cloud gathered through kinematic laser scanning into static and dynamic points. The presented algorithm utilizes a voxel grid data structure and uses a ray intersection test to mark voxels as dynamic. The algorithm does not require any ego-motion estimations, computationally expensive object recognition or tracking of moving objects over time. It is easy to implement and can be executed on many cores in parallel. We show the viability of this approach by applying our algorithm to a dataset that we gathered by mounting a FARO Focus3D Laser scanner onto a skid which was then sent along a production line for consumer car chassis in a factory of the Volkswagen corporation. Since factory operators are interested in acquiring digital models of their production lines without suspending factory operations, the resulting point cloud will contain many dynamic objects like humans or other car bodies. We show how our algorithm is able to successfully remove these dynamic objects from the resulting point cloud with minimal errors. Our implementation is published under a free license as part of 3DTK.}, address = {Ohrid, Macedonia}, author = {Schauer, J. and N{\"u}chter, A.}, booktitle = {Proceedings of the 13th IEEE International Conference on Control and Automation (ICCA '17)}, keywords = {imported}, month = {July}, pages = {701–706}, title = {{Digitizing automotive production lines without interrupting assembly operations through an automatic voxel-based removal of moving objects}}, year = 2017 }
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  Effective Distinction Of Transparent And Specular Reflective Objects In Point Clouds Of A Multi-Echo Laser Scanner Koch, R.; May, S.; Nüchter, A. in Proceedings of the 18th IEEE International Conference on Advanced Robotics (ICAR ’17) (2017). 566–571.
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  A favoured sensor for mapping is a 3D laser scanner since it allows a wide scanning range, precise measurements, and is usable indoor and outdoor. Hence, a mapping module delivers detailed and high resolution maps which makes it possible to navigate safely. Difficulties result from transparent and specular reflective objects which cause erroneous and dubious measurements. At such objects, based on the incident angle, measurements result from the object surface, an object behind the transparent surface, or an object mirrored with respect to the reflective surface. This paper describes an enhanced Pre-Filter-Module to distinguish between these cases. Two experiments demonstrate the usability and show that for single scans the identification of mentioned objects in 3D is possible. The first experiment was made in an empty room with a mirror. The second experiment was made in a stairway which contains a glass door. Further, results show that a discrimination between a specular reflective and a transparent object is possible. Especially for transparent objects the detected size is restricted to the incident angle. That is why future work concentrates on implementing a post-filter module. Gained experience shows that collecting the data of multiple scans and postprocess them as soon as the object was bypassed will improve the map.

  @inproceedings{ICAR2017, abstract = {A favoured sensor for mapping is a 3D laser scanner since it allows a wide scanning range, precise measurements, and is usable indoor and outdoor. Hence, a mapping module delivers detailed and high resolution maps which makes it possible to navigate safely. Difficulties result from transparent and specular reflective objects which cause erroneous and dubious measurements. At such objects, based on the incident angle, measurements result from the object surface, an object behind the transparent surface, or an object mirrored with respect to the reflective surface. This paper describes an enhanced Pre-Filter-Module to distinguish between these cases. Two experiments demonstrate the usability and show that for single scans the identification of mentioned objects in 3D is possible. The first experiment was made in an empty room with a mirror. The second experiment was made in a stairway which contains a glass door. Further, results show that a discrimination between a specular reflective and a transparent object is possible. Especially for transparent objects the detected size is restricted to the incident angle. That is why future work concentrates on implementing a post-filter module. Gained experience shows that collecting the data of multiple scans and postprocess them as soon as the object was bypassed will improve the map.}, address = {Hong Kong, China}, author = {Koch, R. and May, S. and N{\"u}chter, A.}, booktitle = {Proceedings of the 18th IEEE International Conference on Advanced Robotics (ICAR '17)}, keywords = {myown}, month = {July}, pages = {566–571}, title = {{Effective Distinction Of Transparent And Specular Reflective Objects In Point Clouds Of A Multi-Echo Laser Scanner}}, year = 2017 }
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  Evaluating continuous-time SLAM using a predefined trajectory provided by a robotic arm Koch, B.; Leblebici, R.; Martell, A.; Jörissen, S.; Schilling, K.; Nüchter, A. in Proceedings of the ISPRS Geospatial Week 2017, Laserscanning 2017, ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., IV-2/W4 (2017). 17–23.
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  Recently published approaches to SLAM algorithms process laser sensor measurements and output a map as a point cloud of the environment. Often the actual precision of the map remains unclear, since SLAMalgorithms apply local improvements to the resulting map. Unfortunately, it is not trivial to compare the performance of SLAMalgorithms objectively, especially without an accurate ground truth. This paper presents a novel benchmarking technique that allows to compare a precise map generated with an accurate ground truth trajectory to a map with a manipulated trajectory which was distorted by different forms of noise. The accurate ground truth is acquired by mounting a laser scanner on an industrial robotic arm. The robotic arm is moved on a predefined path while the position and orientation of the end-effector tool are monitored. During this process the 2D profile measurements of the laser scanner are recorded in six degrees of freedom and afterwards used to generate a precise point cloud of the test environment. For benchmarking, an offline continuous-time SLAM algorithm is subsequently applied to remove the inserted distortions. Finally, it is shown that the manipulated point cloud is reversible to its previous state and is slightly improved compared to the original version, since small errors that came into account by imprecise assumptions, sensor noise and calibration errors are removed as well.

  @inproceedings{LS2017, abstract = {Recently published approaches to SLAM algorithms process laser sensor measurements and output a map as a point cloud of the environment. Often the actual precision of the map remains unclear, since SLAMalgorithms apply local improvements to the resulting map. Unfortunately, it is not trivial to compare the performance of SLAMalgorithms objectively, especially without an accurate ground truth. This paper presents a novel benchmarking technique that allows to compare a precise map generated with an accurate ground truth trajectory to a map with a manipulated trajectory which was distorted by different forms of noise. The accurate ground truth is acquired by mounting a laser scanner on an industrial robotic arm. The robotic arm is moved on a predefined path while the position and orientation of the end-effector tool are monitored. During this process the 2D profile measurements of the laser scanner are recorded in six degrees of freedom and afterwards used to generate a precise point cloud of the test environment. For benchmarking, an offline continuous-time SLAM algorithm is subsequently applied to remove the inserted distortions. Finally, it is shown that the manipulated point cloud is reversible to its previous state and is slightly improved compared to the original version, since small errors that came into account by imprecise assumptions, sensor noise and calibration errors are removed as well.}, address = {Wuhan, China}, author = {Koch, B. and Leblebici, R. and Martell, A. and J{\"o}rissen, S. and Schilling, K. and N{\"u}chter, A.}, booktitle = {Proceedings of the ISPRS Geospatial Week 2017, Laserscanning 2017}, keywords = {imported}, month = {September}, pages = {17–23}, series = {ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., IV-2/W4}, title = {Evaluating continuous-time SLAM using a predefined trajectory provided by a robotic arm}, year = 2017 }
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  Evaluation of Features from RGB-D Data for Human Body Weight Estimation Pfitzner, C.; May, S.; Nüchter, A. in Proceedings of the 20th World Congress of the International Federation of Automatic Control (IFAC WC ’17) (2017).
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  Body weight is a crucial parameter when it comes to drug or radiation dosing. In case of emergency treatment time is short so that physicians estimate the body weight by the visual appearance of a patient. Further, visual body weight estimation might be a feature for person identification. This paper presents the anthropometric feature extraction from RGB-D sensor data, recorded from frontal view. The features are forwarded to an artificial neural network for weight estimation. Experiments with 233 people demonstrate the capability of different features for body weight estimation. To prove robustness against sensor modalities, a structured light sensor is used, as well as a time-of-flight sensor. An additional experiment including temperature features from a thermal camera improves the body weight estimation beyond.

  @inproceedings{WC2017_2, abstract = {Body weight is a crucial parameter when it comes to drug or radiation dosing. In case of emergency treatment time is short so that physicians estimate the body weight by the visual appearance of a patient. Further, visual body weight estimation might be a feature for person identification. This paper presents the anthropometric feature extraction from RGB-D sensor data, recorded from frontal view. The features are forwarded to an artificial neural network for weight estimation. Experiments with 233 people demonstrate the capability of different features for body weight estimation. To prove robustness against sensor modalities, a structured light sensor is used, as well as a time-of-flight sensor. An additional experiment including temperature features from a thermal camera improves the body weight estimation beyond.}, address = {Toulouse, France}, author = {Pfitzner, C. and May, S. and N{\"u}chter, A.}, booktitle = {Proceedings of the 20th World Congress of the International Federation of Automatic Control (IFAC WC '17)}, keywords = {imported}, month = {July}, title = {{Evaluation of Features from RGB-D Data for Human Body Weight Estimation}}, year = 2017 }
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  Identification of Transparent and Specular Reflective Material in Laser Scans to Discriminate Affected Measurements for Faultless Robotic SLAM Koch, R.; May, S.; Murmann, P.; Nüchter, A. in Journal of Robotics and Autonomous Systems (JRAS) (2017). 87 296–312.
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  Mapping with laser scanners is the state-of-the-art method applied in service, industrial, medical, and rescue robotics. Although a lot of research has been done, maps still suffer from interferences caused by transparent and specular reflective objects. Glass, mirrors, shiny or translucent surfaces cause erroneous measurements depending on the incident angle of the laser beam. In past experiments the Mirror Detector Approach was implemented to determine such measurements with a multi-echo laser scanner. Recognition values are based on their differences in recorded measurements in regard to the distance of the echoes. This paper describes the research to distinguish between reflective and transparent objects. The implemented Mirror Detector was specifically modified for recognition of said objects for which four experiments were conducted; one experiment to show the map of the original Mirror Detector; two experiments to investigate intensity characteristics based on angle, distance, and material; and one experiment to show an applied discrimination with the extended version of the Mirror Detector, the Reflection Classifier Approach. To verify the results, a comparison with existing models was performed. This study showed that shiny metals, like aluminium, etc., provide significant characteristics, while mirrors are to be characterized by a mixed model of glass and shiny metal. Transparent objects turned out to be challenging because their appearance in the sensor data strongly depends on the background. Nevertheless, these experiments show that discrimination of transparent and reflective materials based on the reflected intensity is possible and feasible.

  @article{RAS2017, abstract = {Mapping with laser scanners is the state-of-the-art method applied in service, industrial, medical, and rescue robotics. Although a lot of research has been done, maps still suffer from interferences caused by transparent and specular reflective objects. Glass, mirrors, shiny or translucent surfaces cause erroneous measurements depending on the incident angle of the laser beam. In past experiments the Mirror Detector Approach was implemented to determine such measurements with a multi-echo laser scanner. Recognition values are based on their differences in recorded measurements in regard to the distance of the echoes. This paper describes the research to distinguish between reflective and transparent objects. The implemented Mirror Detector was specifically modified for recognition of said objects for which four experiments were conducted; one experiment to show the map of the original Mirror Detector; two experiments to investigate intensity characteristics based on angle, distance, and material; and one experiment to show an applied discrimination with the extended version of the Mirror Detector, the Reflection Classifier Approach. To verify the results, a comparison with existing models was performed. This study showed that shiny metals, like aluminium, etc., provide significant characteristics, while mirrors are to be characterized by a mixed model of glass and shiny metal. Transparent objects turned out to be challenging because their appearance in the sensor data strongly depends on the background. Nevertheless, these experiments show that discrimination of transparent and reflective materials based on the reflected intensity is possible and feasible.}, author = {Koch, R. and May, S. and Murmann, P. and N{\"u}chter, A.}, journal = {Journal of Robotics and Autonomous Systems (JRAS)}, keywords = {imported}, month = {January}, pages = {296–312}, title = {{Identification of Transparent and Specular Reflective Material in Laser Scans to Discriminate Affected Measurements for Faultless Robotic SLAM}}, volume = 87, year = 2017 }
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  Improving Google’s Cartographer 3D Mapping by Continuous-Time SLAM Nüchter, A.; Bleier, M.; Schauer, J.; Janotta, P. in Proceedings of the 7th ISPRS International Workshop 3D-ARCH 2017: "3D Virtual Reconstruction and Visualization of Complex Architectures", ISPRS Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XLII/W3 (2017). 543–549.
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  This paper shows how to use the result of Google's SLAM solution, called Cartographer, to bootstrap our continuous-time SLAM algorithm. The presented approach optimizes the consistency of the global point cloud, and thus improves on Google’s results. We use the algorithms and data from Google as input for our continuous-time SLAM software. We also successfully applied our software to a similar backpack system which delivers consistent 3D point clouds even in absence of an IMU.

  @inproceedings{3DARCH2017_1, abstract = {This paper shows how to use the result of Google's SLAM solution, called Cartographer, to bootstrap our continuous-time SLAM algorithm. The presented approach optimizes the consistency of the global point cloud, and thus improves on Google’s results. We use the algorithms and data from Google as input for our continuous-time SLAM software. We also successfully applied our software to a similar backpack system which delivers consistent 3D point clouds even in absence of an IMU.}, address = {Nafplio, Greece}, author = {N{\"u}chter, A. and Bleier, M. and Schauer, J. and Janotta, P.}, booktitle = {Proceedings of the 7th ISPRS International Workshop 3D-ARCH 2017: "3D Virtual Reconstruction and Visualization of Complex Architectures"}, keywords = {imported}, month = {March}, pages = {543–549}, series = {ISPRS Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XLII/W3}, title = {{Improving Google's Cartographer 3D Mapping by Continuous-Time SLAM}}, year = 2017 }
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  Low-cost 3D Laser Scanning in Air or Water Using Self-calibrating Structured Light Bleier, M.; Nüchter, A. in Proceedings of the 7th ISPRS International Workshop 3D-ARCH 2017: "3D Virtual Reconstruction and Visualization of Complex Architectures", ISPRS Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XLII/W3 (2017). 105–112.
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  In-situ calibration of structured light scanners in underwater environments is time-consuming and complicated. This paper presents a self-calibrating line laser scanning system, which enables the creation of dense 3D models with a single fixed camera and a freely moving hand-held cross line laser projector. The proposed approach exploits geometric constraints, such as coplanarities, to recover the depth information and is applicable without any prior knowledge of the position and orientation of the laser projector. By employing an off-the-shelf underwater camera and a waterproof housing with high power line lasers an affordable 3D scanning solution can be built. In experiments the performance of the proposed technique is studied and compared with 3D reconstruction using explicit calibration. We demonstrate that the scanning system can be applied to above-the-water as well as underwater scenes.

  @inproceedings{3DARCH2017_2, abstract = {In-situ calibration of structured light scanners in underwater environments is time-consuming and complicated. This paper presents a self-calibrating line laser scanning system, which enables the creation of dense 3D models with a single fixed camera and a freely moving hand-held cross line laser projector. The proposed approach exploits geometric constraints, such as coplanarities, to recover the depth information and is applicable without any prior knowledge of the position and orientation of the laser projector. By employing an off-the-shelf underwater camera and a waterproof housing with high power line lasers an affordable 3D scanning solution can be built. In experiments the performance of the proposed technique is studied and compared with 3D reconstruction using explicit calibration. We demonstrate that the scanning system can be applied to above-the-water as well as underwater scenes.}, address = {Nafplio, Greece}, author = {Bleier, M. and N{\"u}chter, A.}, booktitle = {Proceedings of the 7th ISPRS International Workshop 3D-ARCH 2017: "3D Virtual Reconstruction and Visualization of Complex Architectures"}, keywords = {imported}, month = {March}, pages = {105–112}, series = {ISPRS Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XLII/W3}, title = {{Low-cost 3D Laser Scanning in Air or Water Using Self-calibrating Structured Light}}, year = 2017 }
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  Moving-Object Detection From Consecutive Stereo Pairs Using Slanted Plane Smoothing Chen, L.; Fan, L.; Xie, G.; Huang, K.; Nüchter, A. in IEEE Transactions on Intelligent Transportation Systems (2017). 18(11) 1–10.
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  Detecting moving objects is of great importance for autonomous unmanned vehicle systems, and a challenging task especially in complex dynamic environments. This paper proposes a novel approach for the detection of moving objects and the estimation of their motion states using consecutive stereo image pairs on mobile platforms. First, we use a variant of the semi-global matching algorithm to compute initial disparity maps. Second, assisted by the initial disparities, boundaries in the image segmentation produced by simple linear iterative clustering are classified into coplanar, hinge, and occlusion. Moving points are obtained during ego-motion estimation by a modified random sample consensus) algorithm without resorting to time-consuming dense optical flow. Finally, the moving objects are extracted by merging superpixels according to the boundary types and their movements. The proposed method is accelerated on the GPU at 20 frames per second. The data which we use for testing and benchmarking is released, thus completing similar data sets. It includes 812 image pairs and 924 moving objects with ground truth for better algorithms evaluation. Experimental results demonstrate that the proposed method achieves competitive results in terms of moving-object detection and their motion state estimation in challenging urban scenarios.

  @article{ITS2017, abstract = {Detecting moving objects is of great importance for autonomous unmanned vehicle systems, and a challenging task especially in complex dynamic environments. This paper proposes a novel approach for the detection of moving objects and the estimation of their motion states using consecutive stereo image pairs on mobile platforms. First, we use a variant of the semi-global matching algorithm to compute initial disparity maps. Second, assisted by the initial disparities, boundaries in the image segmentation produced by simple linear iterative clustering are classified into coplanar, hinge, and occlusion. Moving points are obtained during ego-motion estimation by a modified random sample consensus) algorithm without resorting to time-consuming dense optical flow. Finally, the moving objects are extracted by merging superpixels according to the boundary types and their movements. The proposed method is accelerated on the GPU at 20 frames per second. The data which we use for testing and benchmarking is released, thus completing similar data sets. It includes 812 image pairs and 924 moving objects with ground truth for better algorithms evaluation. Experimental results demonstrate that the proposed method achieves competitive results in terms of moving-object detection and their motion state estimation in challenging urban scenarios.}, author = {Chen, L. and Fan, L. and Xie, G. and Huang, K. and Nüchter, A.}, journal = {IEEE Transactions on Intelligent Transportation Systems}, keywords = {myown}, month = {November}, number = 11, pages = {1–10}, title = {Moving-Object Detection From Consecutive Stereo Pairs Using Slanted Plane Smoothing}, volume = 18, year = 2017 }
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  Out of lab calibration of a rotating 2D scanner for 3D mapping Koch, R.; Böttcher, L.; Jahrsdörfer, M.; Maier, J.; Trommer, M.; May, S.; Nüchter, A. in Proceedings of the SPIE optical metrology, Videometrics, Range Imaging, and Applications (2017). (Vol. 10332) 10332 – 10332 .
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  Mapping is an essential task in mobile robotics. To fulfil advanced navigation and manipulation tasks a 3D representation of the environment is required. Applying stereo cameras or Time-of-flight cameras (TOF cameras) are one way to archive this requirement. Unfortunately, they suffer from drawbacks which makes it difficult to map properly. Therefore, costly 3D laser scanners are applied. An inexpensive way to build a 3D representation is to use a 2D laser scanner and rotate the scan plane around an additional axis. A 3D point cloud acquired with such a custom device consists of multiple 2D line scans. Therefore the scanner pose of each line scan need to be determined as well as parameters resulting from a calibration to generate a 3D point cloud. Using external sensor systems are a common method to determine these calibration parameters. This is costly and difficult when the robot needs to be calibrated outside the lab. Thus, this work presents a calibration method applied on a rotating 2D laser scanner. It uses a hardware setup to identify the required parameters for calibration. This hardware setup is light, small, and easy to transport. Hence, an out of lab calibration is possible. Additional a theoretical model was created to test the algorithm and analyse impact of the scanner accuracy. The hardware components of the 3D scanner system are an HOKUYO UTM-30LX-EW 2D laser scanner, a Dynamixel servo-motor, and a control unit. The calibration system consists of an hemisphere. In the inner of the hemisphere a circular plate is mounted. The algorithm needs to be provided with a dataset of a single rotation from the laser scanner. To achieve a proper calibration result the scanner needs to be located in the middle of the hemisphere. By means of geometric formulas the algorithms determine the individual deviations of the placed laser scanner. In order to minimize errors, the algorithm solves the formulas in an iterative process. First, the calibration algorithm was tested with an ideal hemisphere model created in Matlab. Second, laser scanner was mounted differently, the scanner position and the rotation axis was modified. In doing so, every deviation, was compared with the algorithm results. Several measurement settings were tested repeatedly with the 3D scanner system and the calibration system. The results show that the length accuracy of the laser scanner is most critical. It influences the required size of the hemisphere and the calibration accuracy.

  @inproceedings{SPIE2017, abstract = {Mapping is an essential task in mobile robotics. To fulfil advanced navigation and manipulation tasks a 3D representation of the environment is required. Applying stereo cameras or Time-of-flight cameras (TOF cameras) are one way to archive this requirement. Unfortunately, they suffer from drawbacks which makes it difficult to map properly. Therefore, costly 3D laser scanners are applied. An inexpensive way to build a 3D representation is to use a 2D laser scanner and rotate the scan plane around an additional axis. A 3D point cloud acquired with such a custom device consists of multiple 2D line scans. Therefore the scanner pose of each line scan need to be determined as well as parameters resulting from a calibration to generate a 3D point cloud. Using external sensor systems are a common method to determine these calibration parameters. This is costly and difficult when the robot needs to be calibrated outside the lab. Thus, this work presents a calibration method applied on a rotating 2D laser scanner. It uses a hardware setup to identify the required parameters for calibration. This hardware setup is light, small, and easy to transport. Hence, an out of lab calibration is possible. Additional a theoretical model was created to test the algorithm and analyse impact of the scanner accuracy. The hardware components of the 3D scanner system are an HOKUYO UTM-30LX-EW 2D laser scanner, a Dynamixel servo-motor, and a control unit. The calibration system consists of an hemisphere. In the inner of the hemisphere a circular plate is mounted. The algorithm needs to be provided with a dataset of a single rotation from the laser scanner. To achieve a proper calibration result the scanner needs to be located in the middle of the hemisphere. By means of geometric formulas the algorithms determine the individual deviations of the placed laser scanner. In order to minimize errors, the algorithm solves the formulas in an iterative process. First, the calibration algorithm was tested with an ideal hemisphere model created in Matlab. Second, laser scanner was mounted differently, the scanner position and the rotation axis was modified. In doing so, every deviation, was compared with the algorithm results. Several measurement settings were tested repeatedly with the 3D scanner system and the calibration system. The results show that the length accuracy of the laser scanner is most critical. It influences the required size of the hemisphere and the calibration accuracy.}, address = {Munich, Germany}, author = {Koch, R. and B{\"o}ttcher, L. and Jahrsd{\"o}rfer, M. and Maier, J. and Trommer, M. and May, S. and N{\"u}chter, A.}, journal = {Proceedings of the SPIE optical metrology, Videometrics, Range Imaging, and Applications}, keywords = {imported}, month = {June}, pages = {10332 - 10332 - 8}, title = {{Out of lab calibration of a rotating 2D scanner for 3D mapping}}, volume = 10332, year = 2017 }
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  Real-time 3D Mine Modelling in the !VAMOS! Project Bleier, M.; Dias, A.; Ferreira, A.; Pidgeon, J.; Almeida, J.; Silva, E.; Schilling, K.; Nüchter, A. in Real Time Mining, M. Buxton, J. Benndorf (eds.) (2017). 91–102.
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  The project Viable Alternative Mine Operating System (\textexclamdown VAMOS!) develops a new safe, clean and low visibility mining technique for excavating raw materials from submerged inland mines. During operations, the perception data of the mining vehicle can only be communicated to the operator via a computer interface. In order to assist remote control and facilitate assessing risks a detailed view of the mining process below the water surface is necessary. This paper presents approaches to real-time 3D reconstruction of the mining environment for immersive data visualisation in a virtual reality environment to provide advanced spatial awareness. From the raw survey data a more consistent 3D model is created using post-processing techniques based on a continuous-time simultaneous localization and mapping (SLAM) solution. Signed distance function (SDF) based mapping is employed to fuse the measurements from multiple views into a single representation and reduce sensor noise. Results of the proposed techniques are demonstrated on a dataset captured in an sub- merged inland mine.

  @inproceedings{RTM2017, abstract = {The project Viable Alternative Mine Operating System (\textexclamdown VAMOS!) develops a new safe, clean and low visibility mining technique for excavating raw materials from submerged inland mines. During operations, the perception data of the mining vehicle can only be communicated to the operator via a computer interface. In order to assist remote control and facilitate assessing risks a detailed view of the mining process below the water surface is necessary. This paper presents approaches to real-time 3D reconstruction of the mining environment for immersive data visualisation in a virtual reality environment to provide advanced spatial awareness. From the raw survey data a more consistent 3D model is created using post-processing techniques based on a continuous-time simultaneous localization and mapping (SLAM) solution. Signed distance function (SDF) based mapping is employed to fuse the measurements from multiple views into a single representation and reduce sensor noise. Results of the proposed techniques are demonstrated on a dataset captured in an sub- merged inland mine.}, address = {Amsterdam, The Netherlands}, author = {Bleier, M. and Dias, A. and Ferreira, A. and Pidgeon, J. and Almeida, J. and Silva, E. and Schilling, K. and N{\"u}chter, A.}, booktitle = {Real Time Mining}, editor = {Buxton, M. and Benndorf, J.}, keywords = {imported}, month = {October}, pages = {91–102}, publisher = {Technische Universität Bergakademie Freiberg, Institut für Markscheidewesen und Geodäsie}, title = {{Real-time 3D Mine Modelling in the !VAMOS! Project}}, year = 2017 }
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  Signed Distance Function Based Surface Reconstruction of a Submerged Inland Mine Using Continuous-Time SLAM Bleier, M.; Dias, A.; Ferreira, A.; Pidgeon, J.; Almeida, J. M.; Silva, E.; Schilling, K.; Nüchter, A. in Proceedings of the 20th World Congress of the International Federation of Automatic Control (IFAC WC ’17) (2017).
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  The planning of mining operations in water filled open-pit mines requires detailed bathymetry to create a mine plan and assess the involved risks. This paper presents post- processing techniques for creating an improved 3D model from a survey carried out using an autonomous surface vehicle with a multibeam sonar and a GPS/INS navigation system. Inconsistencies of the created point cloud as a result of calibration errors or GPS signal loss are corrected using a continuous-time simultaneous localization and mapping (SLAM) solution. Signed distance function based mapping is employed to fuse the measurements from multiple runs into a consistent representation and reduce sensor noise. From the signed distance function model we reconstruct a 3D surface mesh. We use this terrain model to establish a virtual reality scene for immersive data visualization of the mining operations for testing and planing during development. Results of the proposed approach are demonstrated on a dataset captured in an abandoned submerged inland mine.

  @inproceedings{WC2017_1, abstract = {The planning of mining operations in water filled open-pit mines requires detailed bathymetry to create a mine plan and assess the involved risks. This paper presents post- processing techniques for creating an improved 3D model from a survey carried out using an autonomous surface vehicle with a multibeam sonar and a GPS/INS navigation system. Inconsistencies of the created point cloud as a result of calibration errors or GPS signal loss are corrected using a continuous-time simultaneous localization and mapping (SLAM) solution. Signed distance function based mapping is employed to fuse the measurements from multiple runs into a consistent representation and reduce sensor noise. From the signed distance function model we reconstruct a 3D surface mesh. We use this terrain model to establish a virtual reality scene for immersive data visualization of the mining operations for testing and planing during development. Results of the proposed approach are demonstrated on a dataset captured in an abandoned submerged inland mine.}, address = {Toulouse, France}, author = {Bleier, M. and Dias, A. and Ferreira, A. and Pidgeon, J. and Almeida, J. M. and Silva, E. and Schilling, K. and N{\"u}chter, A.}, booktitle = {Proceedings of the 20th World Congress of the International Federation of Automatic Control (IFAC WC '17)}, keywords = {imported}, month = {July}, title = {{Signed Distance Function Based Surface Reconstruction of a Submerged Inland Mine Using Continuous-Time SLAM}}, year = 2017 }
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  Teach-In für die 3D-Scan Akquise mit einem Roboter Struckmeier, O.; Borrmann, D.; Nüchter, A. in Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beiträge der Oldenburger 3D-Tage 2017, Jade Hochschule (2017). 108–119.
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  Die 3D-Erfassung einer kompletten Umgebung mittels 3D-Laserscanner stellt abhängig von der zu scannenden Umgebung und dem Scanner einen hohen Zeitaufwand für einen menschlichen Operator dar. Der Scanner muss an die einzelnen Scanpositionen bewegt und dort verortet werden. Mit steigender Qualität der Messung nimmt zudem die Dauer der einzelnen Scanvorgänge zu. In diesem Beitrag wird ein Teach-In Ansatz vorgestellt und evaluiert, der den manuelle n Vorgang verkürzt. Dabei führt ein Roboter die vom Vermesser geplanten und eingespeicherten zeitintensiven Schritte automatisch durch und entlastet somit den Bediener.

  @inproceedings{3DTAGE2017, abstract = {Die 3D-Erfassung einer kompletten Umgebung mittels 3D-Laserscanner stellt abhängig von der zu scannenden Umgebung und dem Scanner einen hohen Zeitaufwand für einen menschlichen Operator dar. Der Scanner muss an die einzelnen Scanpositionen bewegt und dort verortet werden. Mit steigender Qualität der Messung nimmt zudem die Dauer der einzelnen Scanvorgänge zu. In diesem Beitrag wird ein Teach-In Ansatz vorgestellt und evaluiert, der den manuelle n Vorgang verkürzt. Dabei führt ein Roboter die vom Vermesser geplanten und eingespeicherten zeitintensiven Schritte automatisch durch und entlastet somit den Bediener.}, author = {Struckmeier, O. and Borrmann, D. and N{\"u}chter, A.}, booktitle = {Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beitr{\"a}ge der Oldenburger 3D-Tage 2017, Jade Hochschule}, keywords = {imported}, month = {February}, pages = {108–119}, title = {{Teach-In f{\"u}r die 3D-Scan Akquise mit einem Roboter}}, year = 2017 }
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  Towards Mobile Mapping of Underground Mines Nüchter, A.; Elseberg, J.; Janotta, P. in Real Time Mining, M. Buxton, J. Benndorf (eds.) (2017). 27–38.
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  Mobile laser scanning systems automate the acquisition of 3D point clouds of environments. The mapping systems are commonly mounted on cars or ships. This paper presents a flexible mapping solution mounted on an underground vehicle, that is able to map underground mines in 3D in walking speeds. A clever choice of hard- and software enables the system to generate 3D maps without using GPS (global positioning system) information and without relying on highly expensive IMU (inertial measurement unit) systems.

  @inproceedings{RTM2017slam, abstract = {Mobile laser scanning systems automate the acquisition of 3D point clouds of environments. The mapping systems are commonly mounted on cars or ships. This paper presents a flexible mapping solution mounted on an underground vehicle, that is able to map underground mines in 3D in walking speeds. A clever choice of hard- and software enables the system to generate 3D maps without using GPS (global positioning system) information and without relying on highly expensive IMU (inertial measurement unit) systems.}, address = {Amsterdam, The Netherlands}, author = {N{\"u}chter, A. and Elseberg, J. and Janotta, P.}, booktitle = {Real Time Mining}, editor = {Buxton, M. and Benndorf, J.}, keywords = {imported}, month = {October}, pages = {27–38}, publisher = {Technische Universität Bergakademie Freiberg, Institut für Markscheidewesen und Geodäsie}, title = {{Towards Mobile Mapping of Underground Mines}}, year = 2017 }
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  Towards Radiometrical Alignment of 3D Point Clouds Lauterbach, H. A.; Borrmann, D.; Nüchter, A. in Proceedings of the 7th ISPRS International Workshop 3D-ARCH 2017: "3D Virtual Reconstruction and Visualization of Complex Architectures", ISPRS Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XLII/W3 (2017). 419–424.
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  3D laser scanners are typically not able to collect color information. Therefore coloring is often done by projecting photos of an additional camera to the 3D scans. The capturing process is time consuming and therefore prone to changes in the environment. The appearance of the colored point cloud is mainly effected by changes of lighting conditions and corresponding camera settings. In case of panorama images these exposure variations are typically corrected by radiometrical aligning the input images to each other. In this paper we adopt existing methods for panorama optimization in order to correct the coloring of point clouds. Therefore corresponding pixels from overlapping images are selected by using geometrically closest points of the registered 3D scans and their neighboring pixels in the images. The dynamic range of images in raw format allows for correction of large exposure differences. Two experiments demonstrate the abilities of the approach.

  @inproceedings{3DARCH2017_3, abstract = {3D laser scanners are typically not able to collect color information. Therefore coloring is often done by projecting photos of an additional camera to the 3D scans. The capturing process is time consuming and therefore prone to changes in the environment. The appearance of the colored point cloud is mainly effected by changes of lighting conditions and corresponding camera settings. In case of panorama images these exposure variations are typically corrected by radiometrical aligning the input images to each other. In this paper we adopt existing methods for panorama optimization in order to correct the coloring of point clouds. Therefore corresponding pixels from overlapping images are selected by using geometrically closest points of the registered 3D scans and their neighboring pixels in the images. The dynamic range of images in raw format allows for correction of large exposure differences. Two experiments demonstrate the abilities of the approach.}, address = {Nafplio, Greece}, author = {Lauterbach, H. A. and Borrmann, D. and N{\"u}chter, A.}, booktitle = {Proceedings of the 7th ISPRS International Workshop 3D-ARCH 2017: "3D Virtual Reconstruction and Visualization of Complex Architectures"}, keywords = {imported}, month = {March}, pages = {419–424}, series = {ISPRS Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XLII/W3}, title = {{Towards Radiometrical Alignment of 3D Point Clouds}}, year = 2017 }
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  Towards robust self-calibration for handheld 3D line laser scanning Bleier, M.; Nüchter, A. in Proceedings of LowCost 3D 2017, ISPRS Int. Archieves Photogrammetry and Remote Sensing, Spatial Inf. Sci., XLII-2/W8 (2017). 31–36.
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  This paper studies self-calibration of a structured light system, which reconstructs 3D information using video from a static consumer camera and a handheld cross line laser projector. Intersections between the individual laser curves and geometric constraints on the relative position of the laser planes are exploited to achieve dense 3D reconstruction. This is possible without any prior knowledge of the movement of the projector. However, inaccurrately extracted laser lines introduce noise in the detected intersection positions and therefore distort the reconstruction result. Furthermore, when scanning objects with specular reflections, such as glossy painted or metalic surfaces, the reflections are often extracted from the camera image as erroneous laser curves. In this paper we investiagte how robust estimates of the parameters of the laser planes can be obtained despite of noisy detections.

  @inproceedings{LC2017, abstract = {This paper studies self-calibration of a structured light system, which reconstructs 3D information using video from a static consumer camera and a handheld cross line laser projector. Intersections between the individual laser curves and geometric constraints on the relative position of the laser planes are exploited to achieve dense 3D reconstruction. This is possible without any prior knowledge of the movement of the projector. However, inaccurrately extracted laser lines introduce noise in the detected intersection positions and therefore distort the reconstruction result. Furthermore, when scanning objects with specular reflections, such as glossy painted or metalic surfaces, the reflections are often extracted from the camera image as erroneous laser curves. In this paper we investiagte how robust estimates of the parameters of the laser planes can be obtained despite of noisy detections.}, address = {Hamburg, Germany}, author = {Bleier, M. and N{\"u}chter, A.}, booktitle = {Proceedings of LowCost 3D 2017}, keywords = {imported}, month = {November}, pages = {31–36}, series = {ISPRS Int. Archieves Photogrammetry and Remote Sensing, Spatial Inf. Sci., XLII-2/W8}, title = {Towards robust self-calibration for handheld 3D line laser scanning}, year = 2017 }

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  Automatische Grundrisserstellung mittels Laserscandaten Borrmann, D.; Leutert, F.; Maurovic, I.; Seder, M.; Nüchter, A. in Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beiträge der Oldenburger 3D-Tage 2016, Jade Hochschule (2016). 108–119.
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  In den letzten Jahren haben sich Laserscanner zum Stand der Technik bei der Erstellung von Gebäudemodellen entwickelt. Im Gegensatz zur vergleichsweise kurzen Aufnahmezeit bei der eigentlichen Erfassung der Umgebung mit dem Scanner nimmt die Nachbearbeitung der Daten einen deutlich höheren Zeitanteil ein. Eine manuelle Datenanalyse ist zeitaufwändig und fehleranfällig. Dies erhöht den Bedarf an automatischen Verfahren zur quantitativen Erfassung und Charakterisierung von Umgebungen. In diesem Beitrag präsentieren wir eine automatische Grundrisserstellung basierend auf dem 3D Toolkit (3DTK - http://www.threedtk.de). Nach der autonomen Akquise mit einem mobilen Roboter werden die Daten mittels des iterativen Verfahrens der nächsten Punkte (engl. Iterative Closest Point (ICP)) registriert. Anschließend erfolgt eine automatische Vektorisierung eines 2D-Schnitts der Umgebung basierend auf Verfahren aus der Bildverarbeitung. Der so erzeugte Grundriss dient als Grundlage für eine semantische Karte.

  @inproceedings{3DTAGE2016, abstract = {In den letzten Jahren haben sich Laserscanner zum Stand der Technik bei der Erstellung von Gebäudemodellen entwickelt. Im Gegensatz zur vergleichsweise kurzen Aufnahmezeit bei der eigentlichen Erfassung der Umgebung mit dem Scanner nimmt die Nachbearbeitung der Daten einen deutlich höheren Zeitanteil ein. Eine manuelle Datenanalyse ist zeitaufwändig und fehleranfällig. Dies erhöht den Bedarf an automatischen Verfahren zur quantitativen Erfassung und Charakterisierung von Umgebungen. In diesem Beitrag präsentieren wir eine automatische Grundrisserstellung basierend auf dem 3D Toolkit (3DTK - http://www.threedtk.de). Nach der autonomen Akquise mit einem mobilen Roboter werden die Daten mittels des iterativen Verfahrens der nächsten Punkte (engl. Iterative Closest Point (ICP)) registriert. Anschließend erfolgt eine automatische Vektorisierung eines 2D-Schnitts der Umgebung basierend auf Verfahren aus der Bildverarbeitung. Der so erzeugte Grundriss dient als Grundlage für eine semantische Karte.}, author = {Borrmann, D. and Leutert, F. and Maurovic, I. and Seder, M. and N{\"u}chter, A.}, booktitle = {Photogrammetrie Laserscanning Optische 3D-Messtechnik, Beitr{\"a}ge der Oldenburger 3D-Tage 2016, Jade Hochschule}, keywords = {imported}, month = {February}, pages = {108–119}, title = {{Automatische Grundrisserstellung mittels Laserscandaten}}, year = 2016 }
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  Effiziente Speicherung großer Punktwolken -- Datenstrukturen für Algorithmen für mobile und terrestrische Laserscansysteme Nüchter, A. in Terrestrisches Laserscanning (TLS 2016) Beiträge zum 154. DVW-Seminar am 28. und 29. November in Fulda (2016). 105–120.
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  @inproceedings{TLS2016, address = {Fulda, Germany}, author = {N{\"u}chter, A.}, booktitle = {Terrestrisches Laserscanning (TLS 2016) Beitr{\"a}ge zum 154. DVW-Seminar am 28. und 29. November in Fulda}, keywords = {imported}, month = {November}, pages = {105–120}, title = {{Effiziente Speicherung großer Punktwolken – Datenstrukturen für Algorithmen für mobile und terrestrische Laserscansysteme}}, year = 2016 }
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  LOCALIZATION CORRECTIONS FOR MOBILE LASER SCANNER USING LOCAL SUPPORT-BASED OUTLIER FILTERING Lehtola, V. V.; Virtanen, J-P.; Rönnholm, P.; Nüchter, A. in Proceedings of the ISPRS Congress 2016, ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci. (2016). 81–88.
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  Following the pioneering work introduced in [Lehtola et al., ISPRS J. Photogramm. Remote Sens. 99, 2015, pp. 25–29], we extend the state-of-the-art intrinsic localization solution for a single two-dimensional (2D) laser scanner from one into (quasi) three dimensions (3D). By intrinsic localization, we mean that no external sensors are used to localize the scanner, such as inertial measurement devices (IMU) or global navigation satellite systems (GNSS). Specifically, the proposed method builds on a novel concept of local support-based filtering of outliers, which enables the use of six degrees-of-freedom (DoF) simultaneous localization and mapping (SLAM) for the purpose of enacting appropriate trajectory corrections into the previous one-dimensional solution. Moreover, the local support-based filtering concept is platform independent, and is therefore likely to be widely generalizable. The here presented overall method is yet limited into quasi-3D by its inability to recover trajectories with steep curvature, but in the future, it may be further extended into full 3D.

  @inproceedings{ISPRSCongress2016, abstract = {Following the pioneering work introduced in [Lehtola et al., ISPRS J. Photogramm. Remote Sens. 99, 2015, pp. 25–29], we extend the state-of-the-art intrinsic localization solution for a single two-dimensional (2D) laser scanner from one into (quasi) three dimensions (3D). By intrinsic localization, we mean that no external sensors are used to localize the scanner, such as inertial measurement devices (IMU) or global navigation satellite systems (GNSS). Specifically, the proposed method builds on a novel concept of local support-based filtering of outliers, which enables the use of six degrees-of-freedom (DoF) simultaneous localization and mapping (SLAM) for the purpose of enacting appropriate trajectory corrections into the previous one-dimensional solution. Moreover, the local support-based filtering concept is platform independent, and is therefore likely to be widely generalizable. The here presented overall method is yet limited into quasi-3D by its inability to recover trajectories with steep curvature, but in the future, it may be further extended into full 3D.}, address = {Prague, Czech Republic}, author = {Lehtola, V. V. and Virtanen, J-P. and R{\"o}nnholm, P. and N{\"u}chter, A.}, booktitle = {Proceedings of the ISPRS Congress 2016}, keywords = {imported}, month = {July}, number = {III-4}, pages = {81–88}, series = {ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci.}, title = {LOCALIZATION CORRECTIONS FOR MOBILE LASER SCANNER USING LOCAL SUPPORT-BASED OUTLIER FILTERING}, year = 2016 }
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  Localization of a Mobile Laser Scanner via Dimensional Reduction Lehtola, V. V.; Virtanen, J.-P.; Vaaja, M. T.; Hyyppä, H.; Nüchter, A. in ISPRS Journal of Photogrammetry and Remote Sensing (JPRS) (2016). 121 48–59.
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  We extend the concept of intrinsic localization from a theoretical one-dimensional (1D) solution onto a 2D manifold that is embedded in a 3D space, and then recover the full six degrees of freedom for a mobile laser scanner with a simultaneous localization and mapping algorithm (SLAM). By intrinsic localization, we mean that no reference coordinate system, such as global navigation satellite system (GNSS), nor inertial measurement unit (IMU) are used. Experiments are conducted with a 2D laser scanner mounted on a rolling prototype platform, VILMA. The concept offers potential in being extendable to other wheeled platforms.

  @article{JPRS2016, abstract = {We extend the concept of intrinsic localization from a theoretical one-dimensional (1D) solution onto a 2D manifold that is embedded in a 3D space, and then recover the full six degrees of freedom for a mobile laser scanner with a simultaneous localization and mapping algorithm (SLAM). By intrinsic localization, we mean that no reference coordinate system, such as global navigation satellite system (GNSS), nor inertial measurement unit (IMU) are used. Experiments are conducted with a 2D laser scanner mounted on a rolling prototype platform, VILMA. The concept offers potential in being extendable to other wheeled platforms.}, author = {Lehtola, V. V. and Virtanen, J.-P. and Vaaja, M. T. and Hyypp{\"a}, H. and N{\"u}chter, A.}, journal = {ISPRS Journal of Photogrammetry and Remote Sensing (JPRS)}, keywords = {imported}, month = {November}, pages = {48–59}, title = {{Localization of a Mobile Laser Scanner via Dimensional Reduction}}, volume = 121, year = 2016 }
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  Multi-Robot Localization and Mapping based on Signed Distance Functions Koch, P.; May, S.; Schmidpeter, M.; Kühn, M.; Pfitzner, C.; Merkl, C.; Koch, R.; Fees, M.; Martin, J.; Nüchter, A. in Journal of Intelligent and Robotic Systems (2016). 83(3) 409–428.
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  This publication describes a 2D Simultaneous Localization and Mapping approach applicable to multiple mobile robots. The presented strategy uses data of 2D LIDAR sensors to build a dynamic representation based on Signed Distance Functions. Novelties of the approach are a joint map built in parallel instead of occasional merging of smaller maps and the limited drift localization which requires no loop closure detection. A multi-threaded software architecture performs registration and data integration in parallel allowing for drift-reduced pose estimation of multiple robots. Experiments are provided demonstrating the application with single and multiple robot mapping using simulated data, public accessible recorded data, two actual robots operating in a comparably large area as well as a deployment of these units at the Robocup rescue league.

  @article{JINT2016, abstract = {This publication describes a 2D Simultaneous Localization and Mapping approach applicable to multiple mobile robots. The presented strategy uses data of 2D LIDAR sensors to build a dynamic representation based on Signed Distance Functions. Novelties of the approach are a joint map built in parallel instead of occasional merging of smaller maps and the limited drift localization which requires no loop closure detection. A multi-threaded software architecture performs registration and data integration in parallel allowing for drift-reduced pose estimation of multiple robots. Experiments are provided demonstrating the application with single and multiple robot mapping using simulated data, public accessible recorded data, two actual robots operating in a comparably large area as well as a deployment of these units at the Robocup rescue league.}, author = {Koch, P. and May, S. and Schmidpeter, M. and Kühn, M. and Pfitzner, C. and Merkl, C. and Koch, R. and Fees, M. and Martin, J. and N{\"u}chter, A.}, journal = {Journal of Intelligent and Robotic Systems}, keywords = {imported}, month = {September}, number = 3, pages = {409–428}, title = {{Multi-Robot Localization and Mapping based on Signed Distance Functions}}, volume = 83, year = 2016 }
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  Neural Network-based Visual Body Weight Estimation for Drug Dosage Finding Pfitzner, C.; May, S.; Nüchter, A. in Proceedings of the SPIE 9784, Medical Imaging 2016: Image Processing (2016).
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  Body weight adapted drug dosages are important for emergency treatments. This paper describes an improved body weight estimation approach for emergency patients in a trauma room, based on images from a RGBD sensor and a thermal camera. The improvements are archived by several extensions: The sensor fusion of RGBD and thermal camera eases filtering and segmentation of the patient's body from the background. Robustness and accuracy is gained by an artificial neural network (ANN), which considers features from the sensors as input to calculate the patient's body weight, e.g. the patient's volume, surface and shape parameters. The ANN is trained offline with 30 percent of the patients data. Preliminary experiments with 69 real patients show an accuracy close to 90 percent for a threshold of ten percent relative error in real body estimation. Results are compared to the patient's self estimation, a physician's guess and an anthropometric method: If the patient is knowledgeable it is the best possibility for body weight adapted drug dosages with 97 percent accuracy. The treating physicians and the anthropometric estimation achieve an accuracy of approximately 70 percent. The here presented approach gets an accuracy of nearly 90 percent and would be the best solution if a patient can not provide his own body weight and can not be weighted on a scale. These preliminary results demonstrate a sufficient approach for an upcoming clinical trial with 1,000 patients for body weight estimation.

  @inproceedings{MedIm2016, abstract = {Body weight adapted drug dosages are important for emergency treatments. This paper describes an improved body weight estimation approach for emergency patients in a trauma room, based on images from a RGBD sensor and a thermal camera. The improvements are archived by several extensions: The sensor fusion of RGBD and thermal camera eases filtering and segmentation of the patient's body from the background. Robustness and accuracy is gained by an artificial neural network (ANN), which considers features from the sensors as input to calculate the patient's body weight, e.g. the patient's volume, surface and shape parameters. The ANN is trained offline with 30 percent of the patients data. Preliminary experiments with 69 real patients show an accuracy close to 90 percent for a threshold of ten percent relative error in real body estimation. Results are compared to the patient's self estimation, a physician's guess and an anthropometric method: If the patient is knowledgeable it is the best possibility for body weight adapted drug dosages with 97 percent accuracy. The treating physicians and the anthropometric estimation achieve an accuracy of approximately 70 percent. The here presented approach gets an accuracy of nearly 90 percent and would be the best solution if a patient can not provide his own body weight and can not be weighted on a scale. These preliminary results demonstrate a sufficient approach for an upcoming clinical trial with 1,000 patients for body weight estimation.}, address = {San Diego, CA, USA}, author = {Pfitzner, C. and May, S. and N{\"u}chter, A.}, booktitle = {Proceedings of the SPIE 9784, Medical Imaging 2016: Image Processing}, keywords = {imported}, month = {February}, title = {Neural Network-based Visual Body Weight Estimation for Drug Dosage Finding}, year = 2016 }
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  Performance comparison between state-of-the-art point-cloud based collision detection approaches on the CPU and GPU Schauer, J.; Bedkowski, J.; Majek, K.; Nüchter, A. in Proceedings of the 4th IFAC Symposium on Telematics Applications (TA ’16) (2016). (Vol. 49) 54–59.
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  We present two fundamentally different approaches to detect collisions between two point clouds and compare their performance on multiple datasets. A collision between points happens if they are closer to each other than a given threshold radius. One approach utilizes the main CPU with a k-d tree datastructure to efficiently carry out fixed range searches around points in 3D while the other mainly executes on a GPU using a regular grid decomposition technique implemented in the CUDA framework. We will show how massively parallel 3D range searches on a grid based datastructure on a GPU performs similarly well as a tree based approach on the CPU with orders of magnitude less parallelization. We also show how each method scales with varying input sizes and how they perform differently well depending on the spatial structure of the input data.

  @inproceedings{TA2016, abstract = {We present two fundamentally different approaches to detect collisions between two point clouds and compare their performance on multiple datasets. A collision between points happens if they are closer to each other than a given threshold radius. One approach utilizes the main CPU with a k-d tree datastructure to efficiently carry out fixed range searches around points in 3D while the other mainly executes on a GPU using a regular grid decomposition technique implemented in the CUDA framework. We will show how massively parallel 3D range searches on a grid based datastructure on a GPU performs similarly well as a tree based approach on the CPU with orders of magnitude less parallelization. We also show how each method scales with varying input sizes and how they perform differently well depending on the spatial structure of the input data.}, address = {Porto Alegre, Brazil}, author = {Schauer, J. and Bedkowski, J. and Majek, K. and N{\"u}chter, A.}, booktitle = {Proceedings of the 4th IFAC Symposium on Telematics Applications (TA '16)}, keywords = {myown}, month = {November}, number = 30, pages = {54–59}, title = {{Performance comparison between state-of-the-art point-cloud based collision detection approaches on the CPU and GPU}}, volume = 49, year = 2016 }
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  Range Sensors Konolige, K.; Nüchter, A. in Handbook of Robotics, B. Siciliano, O. Khatib (eds.) (2016). (second ) 783–810.
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  @incollection{Handbook2016, author = {Konolige, K. and N{\"u}chter, A.}, booktitle = {Handbook of Robotics}, edition = {second}, editor = {Siciliano, B. and Khatib, O.}, keywords = {imported}, pages = {783–810}, publisher = {Springer}, title = {Range Sensors}, year = 2016 }
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  Spatial Projection of Thermal Data for Visual Inspection Leutert, F.; Borrmann, D.; Schilling, K.; Nüchter, A. in Proceedings of the 14th IEEE International Conference on Control, Automation, Robotics and Vision (ICARCV ’16) (2016). 1–6.
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  Since the advent of thermal imaging, devices with a high optical resolution that use detector arrays to capture the emitted radiance in the thermal infrared range of an entire scene simultaneously have developed as a standard in monitoring energy related. They have had a huge impact on the building industry and in manifacturing, where they are commonly used to monitor proecces that require stable temperature conditions. As beneficial as contactless measurements are, the subsequent localization of points of interest in the environment is often difficult. To overcome this problem we propose a portable system that combines thermal imaging with Augmented Reality (AR). The idea of the approach is to project the gathered temperature information back into the scene to facilitate visual inspection.

  @inproceedings{ICARCV2016, abstract = {Since the advent of thermal imaging, devices with a high optical resolution that use detector arrays to capture the emitted radiance in the thermal infrared range of an entire scene simultaneously have developed as a standard in monitoring energy related. They have had a huge impact on the building industry and in manifacturing, where they are commonly used to monitor proecces that require stable temperature conditions. As beneficial as contactless measurements are, the subsequent localization of points of interest in the environment is often difficult. To overcome this problem we propose a portable system that combines thermal imaging with Augmented Reality (AR). The idea of the approach is to project the gathered temperature information back into the scene to facilitate visual inspection.}, address = {Phuket, Thailand}, author = {Leutert, F. and Borrmann, D. and Schilling, K. and N{\"u}chter, A.}, booktitle = {Proceedings of the 14th IEEE International Conference on Control, Automation, Robotics and Vision (ICARCV '16)}, keywords = {imported}, month = {November}, pages = {1–6}, title = {{Spatial Projection of Thermal Data for Visual Inspection}}, year = 2016 }

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  3D Point Cloud Compression using Conventional Image Compression for Efficient Data Transmission Houshiar, H.; Nüchter, A. in Proceedings of the XXV International Symposium on Information, Communication and Automation Technologies (ICAT ’15) (2015). 1–8.
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  Modern 3D laser scanners make it easy to collect large 3D point clouds. In this paper we present the use of conventional image based compression methods for 3D point clouds. We map the point cloud onto panorama images to encode the range, reflectance and color value for each point. An encoding method is presented to map the floating point measured ranges on to a three channel image. The image compression methods are used to compress the generated panorama images. We present the results of several lossless compression methods and the lossy JPEG on point cloud compression. Lossless compression methods are designed to retain the original data. On the other hand lossy compression methods sacrifice the details for higher compression ratio. This produces artefacts in the recovered point cloud data. We study the effects of these artefacts on encoded range data. A filtration process is presented for determination of range outliers from uncompressed point clouds.

  @inproceedings{ICAT2015, abstract = {Modern 3D laser scanners make it easy to collect large 3D point clouds. In this paper we present the use of conventional image based compression methods for 3D point clouds. We map the point cloud onto panorama images to encode the range, reflectance and color value for each point. An encoding method is presented to map the floating point measured ranges on to a three channel image. The image compression methods are used to compress the generated panorama images. We present the results of several lossless compression methods and the lossy JPEG on point cloud compression. Lossless compression methods are designed to retain the original data. On the other hand lossy compression methods sacrifice the details for higher compression ratio. This produces artefacts in the recovered point cloud data. We study the effects of these artefacts on encoded range data. A filtration process is presented for determination of range outliers from uncompressed point clouds.}, address = {Sarajevo, Bosnia}, author = {Houshiar, H. and N{\"u}chter, A.}, booktitle = {Proceedings of the XXV International Symposium on Information, Communication and Automation Technologies (ICAT '15)}, keywords = {imported}, month = {October}, pages = {1–8}, publisher = {IEEE Xplore}, title = {{3D Point Cloud Compression using Conventional Image Compression for Efficient Data Transmission}}, year = 2015 }
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  A Backpack-Mounted 3D Mobile Scanning System Nüchter, A.; Borrmann, D.; Elseberg, J.; Redondo, D. in Allgemeine Vermessungs-Nachrichten (AVN), Special Issue MoLAS 2014 (2015). 122(10) 301–307.
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  Mobile laser scanning systems automate the acquisition of 3D point clouds of environments. The mapping systems are commonly mounted on cars or ships. This paper presents a mapping solution mounted on a backpack. A clever choice of hard- and software enables the system to generate 3D maps without using GPS (global positioning system) information and without relying on expensive IMU (inertial measurement unit) systems. Therefore, it enables flexible indoor mapping.

  @article{AVN2015_2, abstract = {Mobile laser scanning systems automate the acquisition of 3D point clouds of environments. The mapping systems are commonly mounted on cars or ships. This paper presents a mapping solution mounted on a backpack. A clever choice of hard- and software enables the system to generate 3D maps without using GPS (global positioning system) information and without relying on expensive IMU (inertial measurement unit) systems. Therefore, it enables flexible indoor mapping.}, author = {N{\"u}chter, A. and Borrmann, D. and Elseberg, J. and Redondo, D.}, journal = {Allgemeine Vermessungs-Nachrichten (AVN), Special Issue MoLAS 2014}, keywords = {imported}, month = {October}, number = 10, pages = {301–307}, title = {{A Backpack-Mounted 3D Mobile Scanning System}}, volume = 122, year = 2015 }
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  A Man-Portable, IMU-free Mobile Mapping Nüchter, A.; Borrmann, D.; Koch, P.; Kühn, M.; May, S. in Proceedings of the ISPRS Geospatial Week 2015, Laserscanning 2015, ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., II-3/W5 (2015). 17–23.
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  Mobile mapping systems are commonly mounted on cars, ships and robots. The data is directly geo-referenced using GPS data and expensive IMU (inertial measurement systems). Driven by the need for flexible, indoor mapping systems we present an inexpensive mobile mapping solution that can be mounted on a backpack. It combines a horizontally mounted 2D profiler with a constantly spinning 3D laser scanner. The initial system featuring a low-cost MEMS IMU was revealed and demonstrated at MoLaS: Technology Workshop Mobile Laser Scanning at Fraunhofer IPM in Freiburg in November 2014. In this paper, we present an IMU-free solution.

  @inproceedings{LS2015, abstract = {Mobile mapping systems are commonly mounted on cars, ships and robots. The data is directly geo-referenced using GPS data and expensive IMU (inertial measurement systems). Driven by the need for flexible, indoor mapping systems we present an inexpensive mobile mapping solution that can be mounted on a backpack. It combines a horizontally mounted 2D profiler with a constantly spinning 3D laser scanner. The initial system featuring a low-cost MEMS IMU was revealed and demonstrated at MoLaS: Technology Workshop Mobile Laser Scanning at Fraunhofer IPM in Freiburg in November 2014. In this paper, we present an IMU-free solution.}, address = {La Grande Motte, France}, author = {N{\"u}chter, A. and Borrmann, D. and Koch, P. and K{\"u}hn, M. and May, S.}, booktitle = {Proceedings of the ISPRS Geospatial Week 2015, Laserscanning 2015}, keywords = {imported}, month = {September}, pages = {17–23}, series = {ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., II-3/W5}, title = {A Man-Portable, IMU-free Mobile Mapping}, year = 2015 }
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  A Study of Projections for Key Point Based Registration of Panoramic Terrestrial 3D Laser Scans Houshiar, H.; Elseberg, J.; Borrmann, D.; Nüchter, A. in Journal of Geo-spatial Information Science (2015). 18(1) 11–31.
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  This paper surveys state-of-the-art image features and descriptors for the task of 3D scan registration based on panoramic reflectance images. As modern terrestrial laser scanners digitize their environment in a spherical way, the sphere has to be projected to a two-dimensional image. To this end, we evaluate the equirectangular, the cylindrical, the Mercator, the rectilinear, the Pannini, the stereographic, and the z-axis projection. We show that the Mercator and the Pannini projection outperform the other projection methods.

  @article{GSIS2015, abstract = {This paper surveys state-of-the-art image features and descriptors for the task of 3D scan registration based on panoramic reflectance images. As modern terrestrial laser scanners digitize their environment in a spherical way, the sphere has to be projected to a two-dimensional image. To this end, we evaluate the equirectangular, the cylindrical, the Mercator, the rectilinear, the Pannini, the stereographic, and the z-axis projection. We show that the Mercator and the Pannini projection outperform the other projection methods.}, author = {Houshiar, H. and Elseberg, J. and Borrmann, D. and N{\"u}chter, A.}, journal = {Journal of Geo-spatial Information Science}, keywords = {imported}, month = {January}, number = 1, pages = {11–31}, title = {{A Study of Projections for Key Point Based Registration of Panoramic Terrestrial 3D Laser Scans}}, volume = 18, year = 2015 }
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  CASTLE3D -- A Computer Aided System for Labelling Archaeological Excavations in 3D Houshiar, H.; Borrmann, D.; Elseberg, J.; Nüchter, A.; Winkler, S.; Näth, F. in Proceedings of the XXV International CIPA Symposium, ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., II-3/W1 (2015). 111–118.
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  Documentation of archaeological excavation sites with conventional methods and tools such as hand drawings, measuring tape and archaeological notes is time consuming. This process is prone to human errors and the quality of the documentation depends on the qualification of the archaeologist on site. Use of modern technology and methods in 3D surveying and 3D robotics facilitate and improve this process. Computer-aided systems and databases improve the documentation quality and increase the speed of data acquisition. 3D laser scanning is the state of the art in modelling archaeological excavation sites, historical sites and even entire cities or landscapes. Modern laser scanners are capable of data acquisition of up to 1 million points per second. This provides a very detailed 3D point cloud of the environment. 3D point clouds and 3D models of an excavation site provide a better representation of the environment for the archaeologist and for documentation. The point cloud can be used both for further studies on the excavation and for the presentation of results. This paper introduces a Computer aided system for labelling archaeological excavations in 3D (CASTLE3D). Consisting of a set of tools for recording and georeferencing the 3D data from an excavation site, CASTLE3D is a novel documentation approach in industrial archaeology. It provides a 2D and 3D visualisation of the data and an easy-to-use interface that enables the archaeologist to select regions of interest and to interact with the data in both representations. The 2D visualisation and a 3D orthogonal view of the data provide cuts of the environment that resemble the traditional hand drawings. The 3D perspective view gives a realistic view of the environment. CASTLE3D is designed as an easy-to-use on-site semantic mapping tool for archaeologists. Each project contains a predefined set of semantic information that can be used to label findings in the data. Multiple regions of interest can be joined under one label. Further information such as color, orientation and archaeological notes are added to the label to improve the documentation. The available 3D information allows for easy measurements in the data. The full 3D information of a region of interest can be segmented from the entire data. By joining this data from different georeferenced views the full 3D shape of findings is stored. All the generated documentation in CASTLE3D is exported to an XML format and serves as input for other systems and databases. Apart from presenting the functionalities of CASTLE3D we evaluate its documentation process in a sample project. For this purpose we export the data to the Adiuvabit database (http://adiuvabit.de) where more information is added for further analysis. The documentation process is compared to traditional documentation methods and it is shown how the automated system helps in accelerating the documentation process and decreases errors to a minimum.

  @inproceedings{CIPA2015, abstract = {Documentation of archaeological excavation sites with conventional methods and tools such as hand drawings, measuring tape and archaeological notes is time consuming. This process is prone to human errors and the quality of the documentation depends on the qualification of the archaeologist on site. Use of modern technology and methods in 3D surveying and 3D robotics facilitate and improve this process. Computer-aided systems and databases improve the documentation quality and increase the speed of data acquisition. 3D laser scanning is the state of the art in modelling archaeological excavation sites, historical sites and even entire cities or landscapes. Modern laser scanners are capable of data acquisition of up to 1 million points per second. This provides a very detailed 3D point cloud of the environment. 3D point clouds and 3D models of an excavation site provide a better representation of the environment for the archaeologist and for documentation. The point cloud can be used both for further studies on the excavation and for the presentation of results. This paper introduces a Computer aided system for labelling archaeological excavations in 3D (CASTLE3D). Consisting of a set of tools for recording and georeferencing the 3D data from an excavation site, CASTLE3D is a novel documentation approach in industrial archaeology. It provides a 2D and 3D visualisation of the data and an easy-to-use interface that enables the archaeologist to select regions of interest and to interact with the data in both representations. The 2D visualisation and a 3D orthogonal view of the data provide cuts of the environment that resemble the traditional hand drawings. The 3D perspective view gives a realistic view of the environment. CASTLE3D is designed as an easy-to-use on-site semantic mapping tool for archaeologists. Each project contains a predefined set of semantic information that can be used to label findings in the data. Multiple regions of interest can be joined under one label. Further information such as color, orientation and archaeological notes are added to the label to improve the documentation. The available 3D information allows for easy measurements in the data. The full 3D information of a region of interest can be segmented from the entire data. By joining this data from different georeferenced views the full 3D shape of findings is stored. All the generated documentation in CASTLE3D is exported to an XML format and serves as input for other systems and databases. Apart from presenting the functionalities of CASTLE3D we evaluate its documentation process in a sample project. For this purpose we export the data to the Adiuvabit database (http://adiuvabit.de) where more information is added for further analysis. The documentation process is compared to traditional documentation methods and it is shown how the automated system helps in accelerating the documentation process and decreases errors to a minimum.}, address = {Taipei, Taiwan}, author = {Houshiar, H. and Borrmann, D. and Elseberg, J. and N{\"u}chter, A. and Winkler, S. and N{\"a}th, F.}, booktitle = {Proceedings of the XXV International CIPA Symposium}, keywords = {imported}, month = {September}, pages = {111–118}, series = {ISPRS Annals Photogrammetry and Remote Sensing, Spatial Inf. Sci., II-3/W1}, title = {{CASTLE3D – A Computer Aided System for Labelling Archaeological Excavations in 3D}}, year = 2015 }
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  Collision detection between point clouds using an efficient $k$-d tree implementation Schauer, J.; Nüchter, A. in Journal Advanced Engineering Informatics (JAdvEI) (2015). 29(3) 440–458.
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  Context: An important task in civil engineering is the detection of collisions of a 3D model with an environment representation. Existing methods using the structure gauge provide an insufficient measure because the model either rotates or because the trajectory makes tight turns through narrow passages. This is the case in either automotive assembly lines or in narrow train tunnels. Objective: Given two point clouds, one of the environment and one of a model and a trajectory with six degrees of freedom along which the model moves through the environment, find all colliding points of the environment with the model within a certain clearance radius. Method: This paper presents two collision detection (CD) methods called kd-CD and kd-CD-simple and two penetration depth (PD) calculation methods called kd-PD and kd-PD-fast. All four methods are based on searches in a k-d tree representation of the environment. The creation of the k-d tree, its search methods and other features will be explained in the scope of their use to detect collisions and calculate depths of penetration. Results: The algorithms are benchmarked by moving the point cloud of a train wagon with 2.5 million points along the point cloud of a 1144m long train track through a narrow tunnel with overall 18.92 million points. Points where the wagon collides with the tunnel wall are visually highlighted with their penetration depth. With a safety margin of 5cm kd-PD-simple finds all colliding points on its trajectory which is sampled into 19,392 positions in 77s on a standard desktop machine of 1.6GHz. Conclusion: The presented methods for collision detection and penetration depth calculation are shown to solve problems for which the structure gauge is an insufficient measure. The underlying k-d tree is shown to be an effective data structure for the required look-up operations.

  @article{ADVEI2015, abstract = {Context: An important task in civil engineering is the detection of collisions of a 3D model with an environment representation. Existing methods using the structure gauge provide an insufficient measure because the model either rotates or because the trajectory makes tight turns through narrow passages. This is the case in either automotive assembly lines or in narrow train tunnels. Objective: Given two point clouds, one of the environment and one of a model and a trajectory with six degrees of freedom along which the model moves through the environment, find all colliding points of the environment with the model within a certain clearance radius. Method: This paper presents two collision detection (CD) methods called kd-CD and kd-CD-simple and two penetration depth (PD) calculation methods called kd-PD and kd-PD-fast. All four methods are based on searches in a k-d tree representation of the environment. The creation of the k-d tree, its search methods and other features will be explained in the scope of their use to detect collisions and calculate depths of penetration. Results: The algorithms are benchmarked by moving the point cloud of a train wagon with 2.5 million points along the point cloud of a 1144m long train track through a narrow tunnel with overall 18.92 million points. Points where the wagon collides with the tunnel wall are visually highlighted with their penetration depth. With a safety margin of 5cm kd-PD-simple finds all colliding points on its trajectory which is sampled into 19,392 positions in 77s on a standard desktop machine of 1.6GHz. Conclusion: The presented methods for collision detection and penetration depth calculation are shown to solve problems for which the structure gauge is an insufficient measure. The underlying k-d tree is shown to be an effective data structure for the required look-up operations.}, author = {Schauer, J. and N{\"u}chter, A.}, journal = {Journal Advanced Engineering Informatics (JAdvEI)}, keywords = {imported}, month = {August}, number = 3, pages = {440–458}, title = {Collision detection between point clouds using an efficient $k$-d tree implementation}, volume = 29, year = 2015 }
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  Das Castle3D Framework zur fortlaufenden semantischen 3D-Kartierung von archäologischen Ausgrabungsstätten Borrmann, D.; Houshiar, H.; Elseberg, J.; Nüchter, A; Näth, F.; Winkler, S. in Allgemeine Vermessungs-Nachrichten (AVN) (2015). 122(6/7) 233–246.
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  Das 3D Laserscanning ist Stand der Technik bei der Modellierung archäologischer Ausgrabungsstätten, historischer Anlagen und sogar ganzer Städte oder Landschaften. Die Dokumentation der Befunde auf einer Ausgrabungsstätte ist eine wesentliche archäologische Aufgabe. Ein automatisiertes System würde diesen Prozess beschleunigen und die Anzahl der Fehler auf ein Minimum reduzieren. Dieser Beitrag stellt einen neuen Ansatz in der Dokumentation industrieller Archäologie vor durch die Entwicklung einer standardisierten Herangehensweise an die computerunterstützte Dokumentation einer archäologischen Ausgrabungsstätten. Ausserdem wird eine Reihe von Tools zur Erfassung und Registrierung von 3D-Daten auf Ausgrabungsstätten vorgestellt, die den Hauptbestandteil der Arbeitskette abdecken. Wir stellen ein effizientes Werkzeug zur Verfügung für die Visualisierung der erworbenen 3D-Punktwolken im 3D- und 2D-Modus. Der Hauptzweck dieser Software ist Archäologen ein einfach zu bedienendes Tool für die semantische Kartierung vor Ort zu bieten. Es enthält Funktionen für die Auswahl und Kennzeichnung von Funden. Jedes Label kann mit weiteren Informationen versehen werden. Diese Daten werden im XML-Format exportiert und dienen als Eingabe für andere Systeme und Datenbanken.

  @article{AVN2015_1, abstract = {Das 3D Laserscanning ist Stand der Technik bei der Modellierung arch{\"a}ologischer Ausgrabungsst{\"a}tten, historischer Anlagen und sogar ganzer St{\"a}dte oder Landschaften. Die Dokumentation der Befunde auf einer Ausgrabungsst{\"a}tte ist eine wesentliche arch{\"a}ologische Aufgabe. Ein automatisiertes System w{\"u}rde diesen Prozess beschleunigen und die Anzahl der Fehler auf ein Minimum reduzieren. Dieser Beitrag stellt einen neuen Ansatz in der Dokumentation industrieller Arch{\"a}ologie vor durch die Entwicklung einer standardisierten Herangehensweise an die computerunterst{\"u}tzte Dokumentation einer arch{\"a}ologischen Ausgrabungsst{\"a}tten. Ausserdem wird eine Reihe von Tools zur Erfassung und Registrierung von 3D-Daten auf Ausgrabungsst{\"a}tten vorgestellt, die den Hauptbestandteil der Arbeitskette abdecken. Wir stellen ein effizientes Werkzeug zur Verf{\"u}gung f{\"u}r die Visualisierung der erworbenen 3D-Punktwolken im 3D- und 2D-Modus. Der Hauptzweck dieser Software ist Arch{\"a}ologen ein einfach zu bedienendes Tool f{\"u}r die semantische Kartierung vor Ort zu bieten. Es enth{\"a}lt Funktionen f{\"u}r die Auswahl und Kennzeichnung von Funden. Jedes Label kann mit weiteren Informationen versehen werden. Diese Daten werden im XML-Format exportiert und dienen als Eingabe f{\"u}r andere Systeme und Datenbanken.}, author = {Borrmann, D. and Houshiar, H. and Elseberg, J. and N{\"u}chter, A and N{\"a}th, F. and Winkler, S.}, journal = {Allgemeine Vermessungs-Nachrichten (AVN)}, keywords = {imported}, number = {6/7}, pages = {233–246}, title = {Das Castle3D Framework zur fortlaufenden semantischen 3D-Kartierung von archäologischen Ausgrabungsstätten}, volume = 122, year = 2015 }
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  Detection of Specular Reflections in Range Measurements for Faultless Robotic SLAM Koch, R.; May, S.; Koch, P.; Kühn, M.; Nüchter, A. in Proceedings of ROBOT’2015: Second Iberian Robotics Conference, Advances in Robotics, Volume 1, Advances in Intelligent Systems and Computing (2015). (Vol. 114) 133–145.
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  Laser scanners are state-of-the-art devices used for mapping in service, industry, medical and rescue robotics. Although a lot of work has been done in laser-based SLAM, maps still suffer from interferences caused by objects like glass, mirrors and shiny or translucent surfaces. Depending on the surface's reflectivity, a laser beam is deflected such that returned measurements provide wrong distance data. At certain positions phantom-like objects appear. This paper describes a specular reflectance detection approach applicable to the emerging technology of multi-echo laser scanners in order to identify and filter reflective objects. Two filter stages are implemented. The first filter reduces errors in current scans on the fly. A second filter evaluates a set of laser scans, triggered as soon as a reflective surface has been passed. This makes the reflective surface detection more robust and is used to refine the registered map. Experiments demonstrate the detection and elimination of reflection errors. They show improved localization and mapping in environments containing mirrors and large glass fronts is improved.

  @inproceedings{ROBOT2015, abstract = {Laser scanners are state-of-the-art devices used for mapping in service, industry, medical and rescue robotics. Although a lot of work has been done in laser-based SLAM, maps still suffer from interferences caused by objects like glass, mirrors and shiny or translucent surfaces. Depending on the surface's reflectivity, a laser beam is deflected such that returned measurements provide wrong distance data. At certain positions phantom-like objects appear. This paper describes a specular reflectance detection approach applicable to the emerging technology of multi-echo laser scanners in order to identify and filter reflective objects. Two filter stages are implemented. The first filter reduces errors in current scans on the fly. A second filter evaluates a set of laser scans, triggered as soon as a reflective surface has been passed. This makes the reflective surface detection more robust and is used to refine the registered map. Experiments demonstrate the detection and elimination of reflection errors. They show improved localization and mapping in environments containing mirrors and large glass fronts is improved.}, address = {Lisbon, Portugal}, author = {Koch, R. and May, S. and Koch, P. and K{\"u}hn, M. and N{\"u}chter, A.}, booktitle = {Proceedings of ROBOT'2015: Second Iberian Robotics Conference, Advances in Robotics, Volume 1}, keywords = {imported}, pages = {133–145}, publisher = {Springer}, series = {Advances in Intelligent Systems and Computing}, title = {Detection of Specular Reflections in Range Measurements for Faultless Robotic SLAM}, volume = 114, year = 2015 }
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  Enhanced frontier-based exploration for indoor environment with multiple robots Al khawaldah, M.; Nüchter, A. in Advanced Robotics (2015). 28(10) 657–669.
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  n this paper, the exploration and map-building of unknown environment by a team of mobile robots is intensively investigated. A new exploration technique is proposed to increase the exploration efficiency. In particular, the new technique has two main objectives: firstly, it aims at reducing the exploration time and the traveled distance by reducing the overlap which takes place when a certain area in the environment is explored by more than one robot. To achieve this, a new procedure to assign the next target location for each individual robot is proposed. And secondly, it aims at reducing computations complexity required by target selection and path planning tasks. More importantly, the proposed technique obviates the need for environment segmentation complex procedures which is adopted in some previous important research works. The new technique is intensively tested with different environments. The results showed the effectiveness of the proposed technique.

  @article{AR2015, abstract = {n this paper, the exploration and map-building of unknown environment by a team of mobile robots is intensively investigated. A new exploration technique is proposed to increase the exploration efficiency. In particular, the new technique has two main objectives: firstly, it aims at reducing the exploration time and the traveled distance by reducing the overlap which takes place when a certain area in the environment is explored by more than one robot. To achieve this, a new procedure to assign the next target location for each individual robot is proposed. And secondly, it aims at reducing computations complexity required by target selection and path planning tasks. More importantly, the proposed technique obviates the need for environment segmentation complex procedures which is adopted in some previous important research works. The new technique is intensively tested with different environments. The results showed the effectiveness of the proposed technique.}, author = {Al khawaldah, M. and N{\"u}chter, A.}, journal = {Advanced Robotics}, keywords = {imported}, number = 10, pages = {657–669}, title = {{Enhanced frontier-based exploration for indoor environment with multiple robots}}, volume = 28, year = 2015 }
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  Evaluation of a Backpack-Mounted 3D Mobile Scanning System Lauterbach, H. A.; Borrmann, D.; Hess, R.; Eck, D.; Schilling, K.; Nüchter, A. in Remote Sensing (2015). 7(10) 13753–13781.
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  Recently, several backpack-mounted systems, also known as personal laser scanning systems, have been developed. They consist of laser scanners or cameras that are carried by a human operator to acquire measurements of the environment while walking. These systems were first designed to overcome the challenges of mapping indoor environments with doors and stairs. While the human operator inherently has the ability to open doors and to climb stairs, the flexible movements introduce irregularities of the trajectory to the system. To compete with other mapping systems, the accuracy of these systems has to be evaluated. In this paper, we present an extensive evaluation of our backpack mobile mapping system in indoor environments. It is shown that the system can deal with the normal human walking motion, but has problems with irregular jittering. Moreover, we demonstrate the applicability of the backpack in a suitable urban scenario.

  @article{REMSEN2015, abstract = {Recently, several backpack-mounted systems, also known as personal laser scanning systems, have been developed. They consist of laser scanners or cameras that are carried by a human operator to acquire measurements of the environment while walking. These systems were first designed to overcome the challenges of mapping indoor environments with doors and stairs. While the human operator inherently has the ability to open doors and to climb stairs, the flexible movements introduce irregularities of the trajectory to the system. To compete with other mapping systems, the accuracy of these systems has to be evaluated. In this paper, we present an extensive evaluation of our backpack mobile mapping system in indoor environments. It is shown that the system can deal with the normal human walking motion, but has problems with irregular jittering. Moreover, we demonstrate the applicability of the backpack in a suitable urban scenario.}, author = {Lauterbach, H. A. and Borrmann, D. and Hess, R. and Eck, D. and Schilling, K. and N{\"u}chter, A.}, journal = {Remote Sensing}, keywords = {imported}, number = 10, pages = {13753–13781}, title = {Evaluation of a Backpack-Mounted 3D Mobile Scanning System}, volume = 7, year = 2015 }
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  Evaluation of Methods for Robotic Mapping of Cultural Heritage Sites Borrmann, D.; Hess, R.; Eck, D.; Houshiar, H.; Nüchter, A.; Schilling, K. in Proceedings of the 2th IFAC conference on Embedded Systems, Computer Intelligence and Telematics (CESCIT ’15) (2015). 105–110.
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  In archaeological studies the use of new technologies has moved into focus in the past years creating new challenges such as the processing of the massive amounts of data. In this paper we present steps and processes for smart 3D modelling of environments by use of the mobile robot Irma3D. A robot that is equipped with multiple sensors, most importantly a photo camera and a laser scanner, enables the automation of most of the processes, including data acquisition and registration. The robot was tested in the Würzburg Residence. Methods for automatic 3D color reconstructions of cultural heritage sites are evaluated in this paper.

  @inproceedings{CESCIT2015, abstract = {In archaeological studies the use of new technologies has moved into focus in the past years creating new challenges such as the processing of the massive amounts of data. In this paper we present steps and processes for smart 3D modelling of environments by use of the mobile robot Irma3D. A robot that is equipped with multiple sensors, most importantly a photo camera and a laser scanner, enables the automation of most of the processes, including data acquisition and registration. The robot was tested in the Würzburg Residence. Methods for automatic 3D color reconstructions of cultural heritage sites are evaluated in this paper.}, address = {Maribor, Slovenia}, author = {Borrmann, D. and Hess, R. and Eck, D. and Houshiar, H. and N{\"u}chter, A. and Schilling, K.}, booktitle = {Proceedings of the 2th IFAC conference on Embedded Systems, Computer Intelligence and Telematics (CESCIT '15)}, keywords = {imported}, month = {June}, pages = {105–110}, title = {{Evaluation of Methods for Robotic Mapping of Cultural Heritage Sites}}, year = 2015 }
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  Intelligent Mobile System for Improving Spatial Design Support and Security Inside Buildings Bedkowski, J.; Majek, K.; Majek, P.; Musialik, P.; Pelka, M.; Nüchter, A. in Mobile Networks and Applications (2015). 20(6) 1–14.
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  This paper concerns an intelligent mobile application for spatial design support and security domain. Mobility has two aspects in our research: The first one is the usage of mobile robots for 3D mapping of urban areas and for performing some specific tasks. The second mobility aspect is related with a novel Software as a Ser- vice system that allows access to robotic functionalities and data over the Ethernet, thus we demonstrate the use of the novel NVIDIA GRID technology allowing to virtualize the graphic processing unit. We introduce Complex Shape Histogram, a core component of our artificial intelligence engine, used for classifying 3D point clouds with a Support Vector Machine. We use Complex Shape Histograms also for loop closing detection in the simultaneous localization and mapping algorithm. Our intelligent mobile system is built on top of the Qualitative Spatio-Temporal Representa- tion and Reasoning framework. This framework defines an ontology and a semantic model, which are used for building the intelligent mobile user interfaces. We show experiments demonstrating advantages of our approach. In addition, we test our prototypes in the field after the end-user case studies demonstrating a relevant contribution for future intelligent mobile systems that merge mobile robots with novel data centers.

  @article{MNAA2015, abstract = {This paper concerns an intelligent mobile application for spatial design support and security domain. Mobility has two aspects in our research: The first one is the usage of mobile robots for 3D mapping of urban areas and for performing some specific tasks. The second mobility aspect is related with a novel Software as a Ser- vice system that allows access to robotic functionalities and data over the Ethernet, thus we demonstrate the use of the novel NVIDIA GRID technology allowing to virtualize the graphic processing unit. We introduce Complex Shape Histogram, a core component of our artificial intelligence engine, used for classifying 3D point clouds with a Support Vector Machine. We use Complex Shape Histograms also for loop closing detection in the simultaneous localization and mapping algorithm. Our intelligent mobile system is built on top of the Qualitative Spatio-Temporal Representa- tion and Reasoning framework. This framework defines an ontology and a semantic model, which are used for building the intelligent mobile user interfaces. We show experiments demonstrating advantages of our approach. In addition, we test our prototypes in the field after the end-user case studies demonstrating a relevant contribution for future intelligent mobile systems that merge mobile robots with novel data centers.}, author = {Bedkowski, J. and Majek, K. and Majek, P. and Musialik, P. and Pelka, M. and N{\"u}chter, A.}, journal = {Mobile Networks and Applications}, keywords = {imported}, number = 6, pages = {1–14}, title = {{Intelligent Mobile System for Improving Spatial Design Support and Security Inside Buildings}}, volume = 20, year = 2015 }
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  Interpreting Thermal 3D Models of Indoor Environments for Energy Efficiency Demisse, G.; Borrmann, D.; Nüchter, A. in Journal of Intelligent and Robotic Systems (2015). 77(1) 55–72.
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  In recent years 3D models of buildings are used in maintenance and inspection, preservation, and other building related applications. However, the usage of these models is limited because most models are pure representations with no or little associated semantics. In this paper we present a pipeline of techniques used for interior interpretation, object detection, and adding energy related semantics to windows of a 3D thermal model. A sequence of algorithms is presented for building the fundamental semantics of a 3D model. Among other things, these algorithms enable the system to differentiate between objects in a room and objects that are part of the room, e.g. floor, windows. Subsequently, the thermal information is used to construct a stochastic mathematical model– namely Markov Random Field– of the temperature distribution of the detected windows. As a result, the MAP(Maximum a posteriori) framework is used to further label the windows as either open, closed or damaged based upon their temperature distribution. The experimental results showed the robustness of the techniques. Furthermore, a strategy to optimize the free parameters is described, in cases where there is a sample training dataset.

  @article{JINT2015, abstract = {In recent years 3D models of buildings are used in maintenance and inspection, preservation, and other building related applications. However, the usage of these models is limited because most models are pure representations with no or little associated semantics. In this paper we present a pipeline of techniques used for interior interpretation, object detection, and adding energy related semantics to windows of a 3D thermal model. A sequence of algorithms is presented for building the fundamental semantics of a 3D model. Among other things, these algorithms enable the system to differentiate between objects in a room and objects that are part of the room, e.g. floor, windows. Subsequently, the thermal information is used to construct a stochastic mathematical model– namely Markov Random Field– of the temperature distribution of the detected windows. As a result, the MAP(Maximum a posteriori) framework is used to further label the windows as either open, closed or damaged based upon their temperature distribution. The experimental results showed the robustness of the techniques. Furthermore, a strategy to optimize the free parameters is described, in cases where there is a sample training dataset.}, author = {Demisse, G. and Borrmann, D. and N{\"u}chter, A.}, journal = {Journal of Intelligent and Robotic Systems}, keywords = {imported}, month = {January}, number = 1, pages = {55–72}, title = {{Interpreting Thermal 3D Models of Indoor Environments for Energy Efficiency}}, volume = 77, year = 2015 }
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  Libra3D: Body Weight Estimation for Emergency Patients in Clinical Environment with a 3D Structured Light Sensor Pfitzner, C.; May, S.; Merkl, C.; Breuer, L.; Köhrmann, M.; Braun, J.; Dirauf, F.; Nüchter, A. in Proceedings of the IEEE International Conference Robotics and Automation (ICRA ’15) (2015).
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  his paper describes the application of a weight estimation method for emergency patients in clinical environments. The approach applies established algorithms for point cloud processing and filtering to data from a low-cost, structured light sensor. A patient's volume is estimated on the basis of their visible front surface. The approach is currently being tested in the workflow of the emergency room at the Universitätsklinikum Erlangen, Germany. Preliminary results show the accuracy of the approach in relation to other conservative means of weight measurements, for example, by physicians and anthropometric measurements.

  @inproceedings{ICRA2015, abstract = {his paper describes the application of a weight estimation method for emergency patients in clinical environments. The approach applies established algorithms for point cloud processing and filtering to data from a low-cost, structured light sensor. A patient's volume is estimated on the basis of their visible front surface. The approach is currently being tested in the workflow of the emergency room at the Universitätsklinikum Erlangen, Germany. Preliminary results show the accuracy of the approach in relation to other conservative means of weight measurements, for example, by physicians and anthropometric measurements.}, address = {Seattle, WA, USA}, author = {Pfitzner, C. and May, S. and Merkl, C. and Breuer, L. and K{\"o}hrmann, M. and Braun, J. and Dirauf, F. and N{\"u}chter, A.}, booktitle = {Proceedings of the IEEE International Conference Robotics and Automation (ICRA '15)}, keywords = {imported}, month = {May}, title = {{Libra3D: Body Weight Estimation for Emergency Patients in Clinical Environment with a 3D Structured Light Sensor}}, year = 2015 }
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  Mirror Identification and Correction of 3D Point Clouds Käshammer, P.; Nüchter, A. in Proceedings of the 6th ISPRS International Workshop 3D-ARCH 2015: "3D Virtual Reconstruction and Visualization of Complex Architectures", IISPRS Archives Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XL-5/W4 (2015). 109–114.
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  In terrestrial laser scanning (TLS), the surface geometry of objects is scanned by laser beams and recorded digitally. This produces a discrete set of scan points, commonly referred to as a point cloud. The coordinates of the scan points are determined by measuring the angles and the time-of-flight relative to the origin (scanner position). However, if it comes to mirror surfaces laser beams are fully reflected, due to the high reflectivity. Mirrors do not appear in the point cloud at all. Instead, for every reflected beam, a incorrect scan point is created behind the actual mirror plane. Consequently, problems arise in multiple derived application fields such as 3D virtual reconstruction of complex architectures. The paper presents a new approach to automatically detect framed rectangular mirrors with known dimensions and to correct the 3D point cloud, using the calculated mirror plane.

  @inproceedings{3DARCH2015_1, abstract = {In terrestrial laser scanning (TLS), the surface geometry of objects is scanned by laser beams and recorded digitally. This produces a discrete set of scan points, commonly referred to as a point cloud. The coordinates of the scan points are determined by measuring the angles and the time-of-flight relative to the origin (scanner position). However, if it comes to mirror surfaces laser beams are fully reflected, due to the high reflectivity. Mirrors do not appear in the point cloud at all. Instead, for every reflected beam, a incorrect scan point is created behind the actual mirror plane. Consequently, problems arise in multiple derived application fields such as 3D virtual reconstruction of complex architectures. The paper presents a new approach to automatically detect framed rectangular mirrors with known dimensions and to correct the 3D point cloud, using the calculated mirror plane.}, address = {Avila, Spain}, author = {K{\"a}shammer, P. and N{\"u}chter, A.}, booktitle = {Proceedings of the 6th ISPRS International Workshop 3D-ARCH 2015: "3D Virtual Reconstruction and Visualization of Complex Architectures"}, keywords = {imported}, month = {February}, pages = {109–114}, series = {IISPRS Archives Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XL-5/W4}, title = {{Mirror Identification and Correction of 3D Point Clouds}}, year = 2015 }
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  Multi-Robot Localization and Mapping based on Signed Distance Functions Koch, P.; May, S.; Schmidpeter, M.; Kühn, M.; Pfitzner, C.; Merkl, C.; Koch, R.; Fees, M.; Martin, J.; Nüchter, A. in Proceedings of the IEEE International Conference on Autonomous Robot Systems and Competitions (ICARSC ’15) (2015). 77–82.
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  This publication describes a 2D Simultaneous Localization and Mapping approach applicable to multiple mobile robots. The presented strategy uses data of 2D LIDAR sensors to build a dynamic representation based on Signed Distance Functions. A multi-threaded software architecture performs registration and data integration in parallel allowing for drift-reduced pose estimation of multiple robots. Experiments are provided demonstrating the application with single and multiple robot mapping using simulated data, public accessible recorded data as well as two actual robots operating in a comparably large area.

  @inproceedings{ICARSC2015, abstract = {This publication describes a 2D Simultaneous Localization and Mapping approach applicable to multiple mobile robots. The presented strategy uses data of 2D LIDAR sensors to build a dynamic representation based on Signed Distance Functions. A multi-threaded software architecture performs registration and data integration in parallel allowing for drift-reduced pose estimation of multiple robots. Experiments are provided demonstrating the application with single and multiple robot mapping using simulated data, public accessible recorded data as well as two actual robots operating in a comparably large area.}, address = {Vila Real, Portugal}, author = {Koch, P. and May, S. and Schmidpeter, M. and K{\"u}hn, M. and Pfitzner, C. and Merkl, C. and Koch, R. and Fees, M. and Martin, J. and N{\"u}chter, A.}, booktitle = {Proceedings of the IEEE International Conference on Autonomous Robot Systems and Competitions (ICARSC '15)}, keywords = {imported}, month = {April}, pages = {77–82}, title = {{Multi-Robot Localization and Mapping based on Signed Distance Functions}}, year = 2015 }
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  Robotic Mapping of Cultural Heritage Sites Borrmann, D.; Hess, R.; Eck, D.; Nüchter, A.; Schilling, K. in Proceedings of the 6th ISPRS International Workshop 3D-ARCH 2015: "3D Virtual Reconstruction and Visualization of Complex Architectures", ISPRS Archives Archives Photogrammetry and Remote Senssing Spatial Inf. Sci., Volume XL-5/W4 (2015). 9–16.
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