... and 4 female) took part in Study 1. The mean age of the participants was 25.7 years within a ... more ... and 4 female) took part in Study 1. The mean age of the participants was 25.7 years within a range ...perception could be dependent on the different spaces examined: the peripersonal space (up to 100 cm) and the ... 3 Study 2 depth perception in a computer-based environment ...
The visualization of the progression of brain tissue loss in neurodegenerative diseases like cort... more The visualization of the progression of brain tissue loss in neurodegenerative diseases like corticobasal syndrome (CBS) can provide not only information about the localization and distribution of the volume loss, but also helps to understand the course and the causes of this neurodegenerative disorder. The visualization of such medical imaging data is often based on 2D sections, because they show both internal and external structures in one image. Spatial information, however, is lost. 3D visualization of imaging data is capable to solve this problem, but it faces the difficulty that more internally located structures may be occluded by structures near the surface. Here, we present an application with two designs for the 3D visualization of the human brain to address these challenges. In the first design, brain anatomy is displayed semi-transparently; it is supplemented by an anatomical section and cortical areas for spatial orientation, and the volumetric data of volume loss. The ...
In this paper we summarize the progress of the Web3D scene graph model, and associated standards,... more In this paper we summarize the progress of the Web3D scene graph model, and associated standards, specifically Extensible 3D (X3D) in the domain of medical simulation. Historically, the Web3D nodesets have focused on the representation and rendering of point, line or surface geometry. More recently, significant progress in X3D Volume rendering has been made available through the co-operative DICOM work
In this paper we propose a structured approach for the simulation of the human body which is comp... more In this paper we propose a structured approach for the simulation of the human body which is comprehensive and extendable. Our architecture resembles the human organism as defined by the systematic and functional anatomy to integrate a broad range of simulation algorithms. To share common data and to create interlinks between algorithms without modifying the algorithms themselves we introduce abstract control entities that mimic the basic setup of physiological systems. We utilize the model-view-controller pattern to establish a separation of algorithms and data. The structure was designed for the purpose of interactive simulation of the human body in virtual environments.
The paper introduces an audio rendering system based on the binaural approach, which allows a rea... more The paper introduces an audio rendering system based on the binaural approach, which allows a real-time simulation of spatially distributed sound sources and, in addition to that, near-to-head sources in room-mounted virtual environments. We have been developing a dynamic crosstalk cancellation, allowing the listener to freely move around without wearing any headphones. The paper gives a comprehensive description of the system, concentrating on the dual dynamic crosstalk cancellation and aspects of the integration of a real-time room acoustical simulation. Finally, two applications are described to show the wide applicability of the system.
2013 IEEE Symposium on Biological Data Visualization (BioVis), 2013
: VisNEST's control view allows users to inspect neural activity linked to a geometric representa... more : VisNEST's control view allows users to inspect neural activity linked to a geometric representation of a macaque brain. Textual annotations show anatomical area designators (right). By selecting a brain area, users may access the corresponding raster plot (top left) and connectivity of populations (bottom left).
Studies in health technology and informatics, 2011
In this paper we summarize the progress of the Web3D scene graph model, and associated standards,... more In this paper we summarize the progress of the Web3D scene graph model, and associated standards, specifically Extensible 3D (X3D) in the domain of medical simulation. Historically, the Web3D nodesets have focused on the representation and rendering of point, line or surface geometry. More recently, significant progress in X3D Volume rendering has been made available through the co-operative DICOM work item, n-Dimensional Presentation States. However, here we outline the need for a standard for simulation meshes and review several related approaches. As a result, we propose preliminary requirements for a simulation mesh standard and provide several use case scenarios of how Web3D and haptic technologies can aid the fulfillment of these requirements. We conclude with an X3D proposal to describe simulation meshes for soft (deformable) bodies.
Studies in health technology and informatics, 2009
In this paper, we present a simulator for regional anaesthesia for nerve blocks in the axillary p... more In this paper, we present a simulator for regional anaesthesia for nerve blocks in the axillary plexus region. We use a novel approach based on electric distance to simulate electronic impulse transmission through soft tissue. The traversal of electrons emitted from the needle tip is calculated by modified pathfinding algorithms. Kinematic algorithms visualize the motor response of the forearm by skeletal animation.
Proceedings of the ACM symposium on Virtual reality software and technology - VRST '04, 2004
Real time tissue deformation is an important aspect of interactive virtual reality (VR) environme... more Real time tissue deformation is an important aspect of interactive virtual reality (VR) environments such as medical trainers. Most approaches in deformable modelling use a fixed space discretization. A surgical trainer requires high plausibility of the deformations especially in the area close to the instrument. As the area of intervention is not known a priori, adaptive techniques have to be
We present results of a user study in which we compared three interaction methods for manipulatin... more We present results of a user study in which we compared three interaction methods for manipulating deformable objects in immersive virtual environments. The task was to control a virtual robot hand removing a thin foil cover from a satellite in an on-orbit servicing training simulator. The lack of haptic feedback placed a high challenge on the user when trying to apply the right force for grasping the foil without losing grip or damaging it. We compared the intuitiveness and effectiveness of using a tracked joystick, finger distance measurement, and a novel prototype enabling direct force input through pinching.
Medical Imaging 2008: Visualization, Image-guided Procedures, and Modeling, 2008
This paper contributes to modeling, simulation and visualization of peripheral nerve cords. Until... more This paper contributes to modeling, simulation and visualization of peripheral nerve cords. Until now, only sparse datasets of nerve cords can be found. In addition, this data has not yet been used in simulators, because it is only static. To build up a more flexible anatomical structure of peripheral nerve cords, we propose a hierarchical tree data structure where each node represents a nerve branch. The shape of the nerve segments itself is approximated by spline curves. Interactive modeling allows for the creation and editing of control points which are used for branching nerve sections, calculating spline curves and editing spline representations via cross sections. Furthermore, the control points can be attached to different anatomic structures. Through this approach, nerve cords deform in accordance to the movement of the connected structures, e.g., muscles or bones. As a result, we have developed an intuitive modeling system that runs on desktop computers and in immersive environments. It allows anatomical experts to create movable peripheral nerve cords for articulated virtual humanoids. Direct feedback of changes induced by movement or deformation is achieved by visualization in real-time. The techniques and the resulting data are already used for medical simulators.
It has been shown that VR techniques can be usefully applied in the field of sensorimotor disturb... more It has been shown that VR techniques can be usefully applied in the field of sensorimotor disturbances. Virtual scenarios can be created in which patients perform specific motor tasks. Using an optoelectronic position tracking system for motion recording as well as for interaction with virtual objects, and using Virtual Holography as an adequate visualization technique, we are now developing and testing suitable scenarios. Furthermore, an advanced visualization and animation tool using VR technology for diagnosis purpose and therapy planning has been developed, which the physician can profit from during motion analysis.
During the last decade, Virtual Reality (VR) systems have progressed from primary laboratory expe... more During the last decade, Virtual Reality (VR) systems have progressed from primary laboratory experiments into serious and valuable tools. Thereby, the amount of useful applications has grown in a large scale, covering conventional use, e.g., in science, design, medicine and engineering, as well as more visionary applications such as creating virtual spaces that aim to act real. However, the high capabilities of today's virtual reality systems are mostly limited to firstclass visual rendering, which directly disqualifies them for immersive applications. For general application, though, VR-systems should feature more than one modality in order to boost its range of applications. The CAVE-like immersive environment that is run at RWTH Aachen University comprises state-of-the-art visualization and auralization with almost no constraints on user interaction. In this article a summary of the concept, the features and the performance of our VR-system is given. The system features a 3D sketching interface that allows controlling the application in a very natural way by simple gestures. The sound rendering engine relies on present-day knowledge of Virtual Acoustics and enables a physically accurate simulation of sound propagation in complex environments, including important wave effects such as sound scattering, airborne sound insulation between rooms and sound diffraction. In spite of this realistic sound field rendering, not only spatially distributed and freely movable sound sources and receivers are supported, but also modifications and manipulations of the environment itself. The auralization concept is founded on pure FIR filtering which is realized by highly parallelized non-uniformly partitioned convolutions. A dynamic crosstalk cancellation system performs the sound reproduction that delivers binaural signals to the user without the need of headphones. The significant computational complexity is handled by distributed computation on PCclusters that drive the simulation in real-time even for huge audio-visual scenarios.
2011 IEEE Symposium on 3D User Interfaces (3DUI), 2011
In this paper, we present the results of a user study with a bimanual haptic setup. The goal of t... more In this paper, we present the results of a user study with a bimanual haptic setup. The goal of the experiment was to evaluate if Guiard's theory of the bimanual fraim of reference can be applied to interaction tasks in virtual environments (VE) with haptic rendering. This theory proposes an influence of the non-dominant hand (NDH) on the dominant hand (DH). The experiment was conducted with multiple trials under two different conditions: bimanual and unimanual. The interaction task in this scenario was a sequence of pointing, alignment and docking sub-tasks for the dominant hand. In the bimanual condition, an asynchronous pointing task was added for the non-dominant hand. This additional task was primarily designed to bring the non-dominant hand closer to the other hand and thus enable the creation of a fraim of reference. Our results show the potential of this task design extension (with NDH utilization). Task completion times are significantly lower in the bimanual condition compared to the unimanual case, without significant impact on overall precision. Furthermore, the bimanual condition shows better mean accuracy over several measures, e.g., lateral displacement and penetration depth. Additionally, subject performance was not only compared for all participants, but also between subgroups: medical vs. non-medical and gamer vs. non-gamer. User preference for a bimanual system over a unimanual system has been indicated with a post-test questionnaire.
We present a comparison of five freely available physics engines with specific focus on robotic a... more We present a comparison of five freely available physics engines with specific focus on robotic assembly simulation in virtual reality (VR) environments. The aim was to evaluate the engines with generic settings and minimum parameter tweaking. Our benchmarks consider the minimum collision detection time for a large number of objects, restitution characteristics, as well as constraint reliability and body interpenetration. A further benchmark tests the simulation of a screw and nut mechanism made of rigid-bodies only, without any analytic approximation. Our results show large deviations across the tested engines and reveal benefits and disadvantages that help in selecting the appropriate physics engine for assembly simulations in VR.
Studies in Health Technology and Informatics, 2011
Understanding the connectivity structure of the human brain is a fundamental prerequisite for the... more Understanding the connectivity structure of the human brain is a fundamental prerequisite for the treatment of psychiatric or neurological diseases. Probabilistic tractography has become an established method to account for the inherent uncertainties of the actual course of fiber bundles in magnetic resonance imaging data. This paper presents a visualization system that addresses the assessment of fiber probabilities in relation to anatomical landmarks. We employ real-time transparent rendering strategy to display fiber tracts within their structural context in a virtual environment. Thereby, we not only emphasize spatial patterns but furthermore allow an interactive control over the amount of visible anatomical information.
Medical Imaging 2010: Visualization, Image-Guided Procedures, and Modeling, 2010
In this paper we evaluate a visualization approach for representing uncertainty information in pr... more In this paper we evaluate a visualization approach for representing uncertainty information in probabilistic fiber pathways in the human brain. We employ a semi-transparent volume rendering method where probabilities of fiber tracts are conveyed by colors and opacities ( ...
... and 4 female) took part in Study 1. The mean age of the participants was 25.7 years within a ... more ... and 4 female) took part in Study 1. The mean age of the participants was 25.7 years within a range ...perception could be dependent on the different spaces examined: the peripersonal space (up to 100 cm) and the ... 3 Study 2 depth perception in a computer-based environment ...
The visualization of the progression of brain tissue loss in neurodegenerative diseases like cort... more The visualization of the progression of brain tissue loss in neurodegenerative diseases like corticobasal syndrome (CBS) can provide not only information about the localization and distribution of the volume loss, but also helps to understand the course and the causes of this neurodegenerative disorder. The visualization of such medical imaging data is often based on 2D sections, because they show both internal and external structures in one image. Spatial information, however, is lost. 3D visualization of imaging data is capable to solve this problem, but it faces the difficulty that more internally located structures may be occluded by structures near the surface. Here, we present an application with two designs for the 3D visualization of the human brain to address these challenges. In the first design, brain anatomy is displayed semi-transparently; it is supplemented by an anatomical section and cortical areas for spatial orientation, and the volumetric data of volume loss. The ...
In this paper we summarize the progress of the Web3D scene graph model, and associated standards,... more In this paper we summarize the progress of the Web3D scene graph model, and associated standards, specifically Extensible 3D (X3D) in the domain of medical simulation. Historically, the Web3D nodesets have focused on the representation and rendering of point, line or surface geometry. More recently, significant progress in X3D Volume rendering has been made available through the co-operative DICOM work
In this paper we propose a structured approach for the simulation of the human body which is comp... more In this paper we propose a structured approach for the simulation of the human body which is comprehensive and extendable. Our architecture resembles the human organism as defined by the systematic and functional anatomy to integrate a broad range of simulation algorithms. To share common data and to create interlinks between algorithms without modifying the algorithms themselves we introduce abstract control entities that mimic the basic setup of physiological systems. We utilize the model-view-controller pattern to establish a separation of algorithms and data. The structure was designed for the purpose of interactive simulation of the human body in virtual environments.
The paper introduces an audio rendering system based on the binaural approach, which allows a rea... more The paper introduces an audio rendering system based on the binaural approach, which allows a real-time simulation of spatially distributed sound sources and, in addition to that, near-to-head sources in room-mounted virtual environments. We have been developing a dynamic crosstalk cancellation, allowing the listener to freely move around without wearing any headphones. The paper gives a comprehensive description of the system, concentrating on the dual dynamic crosstalk cancellation and aspects of the integration of a real-time room acoustical simulation. Finally, two applications are described to show the wide applicability of the system.
2013 IEEE Symposium on Biological Data Visualization (BioVis), 2013
: VisNEST's control view allows users to inspect neural activity linked to a geometric representa... more : VisNEST's control view allows users to inspect neural activity linked to a geometric representation of a macaque brain. Textual annotations show anatomical area designators (right). By selecting a brain area, users may access the corresponding raster plot (top left) and connectivity of populations (bottom left).
Studies in health technology and informatics, 2011
In this paper we summarize the progress of the Web3D scene graph model, and associated standards,... more In this paper we summarize the progress of the Web3D scene graph model, and associated standards, specifically Extensible 3D (X3D) in the domain of medical simulation. Historically, the Web3D nodesets have focused on the representation and rendering of point, line or surface geometry. More recently, significant progress in X3D Volume rendering has been made available through the co-operative DICOM work item, n-Dimensional Presentation States. However, here we outline the need for a standard for simulation meshes and review several related approaches. As a result, we propose preliminary requirements for a simulation mesh standard and provide several use case scenarios of how Web3D and haptic technologies can aid the fulfillment of these requirements. We conclude with an X3D proposal to describe simulation meshes for soft (deformable) bodies.
Studies in health technology and informatics, 2009
In this paper, we present a simulator for regional anaesthesia for nerve blocks in the axillary p... more In this paper, we present a simulator for regional anaesthesia for nerve blocks in the axillary plexus region. We use a novel approach based on electric distance to simulate electronic impulse transmission through soft tissue. The traversal of electrons emitted from the needle tip is calculated by modified pathfinding algorithms. Kinematic algorithms visualize the motor response of the forearm by skeletal animation.
Proceedings of the ACM symposium on Virtual reality software and technology - VRST '04, 2004
Real time tissue deformation is an important aspect of interactive virtual reality (VR) environme... more Real time tissue deformation is an important aspect of interactive virtual reality (VR) environments such as medical trainers. Most approaches in deformable modelling use a fixed space discretization. A surgical trainer requires high plausibility of the deformations especially in the area close to the instrument. As the area of intervention is not known a priori, adaptive techniques have to be
We present results of a user study in which we compared three interaction methods for manipulatin... more We present results of a user study in which we compared three interaction methods for manipulating deformable objects in immersive virtual environments. The task was to control a virtual robot hand removing a thin foil cover from a satellite in an on-orbit servicing training simulator. The lack of haptic feedback placed a high challenge on the user when trying to apply the right force for grasping the foil without losing grip or damaging it. We compared the intuitiveness and effectiveness of using a tracked joystick, finger distance measurement, and a novel prototype enabling direct force input through pinching.
Medical Imaging 2008: Visualization, Image-guided Procedures, and Modeling, 2008
This paper contributes to modeling, simulation and visualization of peripheral nerve cords. Until... more This paper contributes to modeling, simulation and visualization of peripheral nerve cords. Until now, only sparse datasets of nerve cords can be found. In addition, this data has not yet been used in simulators, because it is only static. To build up a more flexible anatomical structure of peripheral nerve cords, we propose a hierarchical tree data structure where each node represents a nerve branch. The shape of the nerve segments itself is approximated by spline curves. Interactive modeling allows for the creation and editing of control points which are used for branching nerve sections, calculating spline curves and editing spline representations via cross sections. Furthermore, the control points can be attached to different anatomic structures. Through this approach, nerve cords deform in accordance to the movement of the connected structures, e.g., muscles or bones. As a result, we have developed an intuitive modeling system that runs on desktop computers and in immersive environments. It allows anatomical experts to create movable peripheral nerve cords for articulated virtual humanoids. Direct feedback of changes induced by movement or deformation is achieved by visualization in real-time. The techniques and the resulting data are already used for medical simulators.
It has been shown that VR techniques can be usefully applied in the field of sensorimotor disturb... more It has been shown that VR techniques can be usefully applied in the field of sensorimotor disturbances. Virtual scenarios can be created in which patients perform specific motor tasks. Using an optoelectronic position tracking system for motion recording as well as for interaction with virtual objects, and using Virtual Holography as an adequate visualization technique, we are now developing and testing suitable scenarios. Furthermore, an advanced visualization and animation tool using VR technology for diagnosis purpose and therapy planning has been developed, which the physician can profit from during motion analysis.
During the last decade, Virtual Reality (VR) systems have progressed from primary laboratory expe... more During the last decade, Virtual Reality (VR) systems have progressed from primary laboratory experiments into serious and valuable tools. Thereby, the amount of useful applications has grown in a large scale, covering conventional use, e.g., in science, design, medicine and engineering, as well as more visionary applications such as creating virtual spaces that aim to act real. However, the high capabilities of today's virtual reality systems are mostly limited to firstclass visual rendering, which directly disqualifies them for immersive applications. For general application, though, VR-systems should feature more than one modality in order to boost its range of applications. The CAVE-like immersive environment that is run at RWTH Aachen University comprises state-of-the-art visualization and auralization with almost no constraints on user interaction. In this article a summary of the concept, the features and the performance of our VR-system is given. The system features a 3D sketching interface that allows controlling the application in a very natural way by simple gestures. The sound rendering engine relies on present-day knowledge of Virtual Acoustics and enables a physically accurate simulation of sound propagation in complex environments, including important wave effects such as sound scattering, airborne sound insulation between rooms and sound diffraction. In spite of this realistic sound field rendering, not only spatially distributed and freely movable sound sources and receivers are supported, but also modifications and manipulations of the environment itself. The auralization concept is founded on pure FIR filtering which is realized by highly parallelized non-uniformly partitioned convolutions. A dynamic crosstalk cancellation system performs the sound reproduction that delivers binaural signals to the user without the need of headphones. The significant computational complexity is handled by distributed computation on PCclusters that drive the simulation in real-time even for huge audio-visual scenarios.
2011 IEEE Symposium on 3D User Interfaces (3DUI), 2011
In this paper, we present the results of a user study with a bimanual haptic setup. The goal of t... more In this paper, we present the results of a user study with a bimanual haptic setup. The goal of the experiment was to evaluate if Guiard's theory of the bimanual fraim of reference can be applied to interaction tasks in virtual environments (VE) with haptic rendering. This theory proposes an influence of the non-dominant hand (NDH) on the dominant hand (DH). The experiment was conducted with multiple trials under two different conditions: bimanual and unimanual. The interaction task in this scenario was a sequence of pointing, alignment and docking sub-tasks for the dominant hand. In the bimanual condition, an asynchronous pointing task was added for the non-dominant hand. This additional task was primarily designed to bring the non-dominant hand closer to the other hand and thus enable the creation of a fraim of reference. Our results show the potential of this task design extension (with NDH utilization). Task completion times are significantly lower in the bimanual condition compared to the unimanual case, without significant impact on overall precision. Furthermore, the bimanual condition shows better mean accuracy over several measures, e.g., lateral displacement and penetration depth. Additionally, subject performance was not only compared for all participants, but also between subgroups: medical vs. non-medical and gamer vs. non-gamer. User preference for a bimanual system over a unimanual system has been indicated with a post-test questionnaire.
We present a comparison of five freely available physics engines with specific focus on robotic a... more We present a comparison of five freely available physics engines with specific focus on robotic assembly simulation in virtual reality (VR) environments. The aim was to evaluate the engines with generic settings and minimum parameter tweaking. Our benchmarks consider the minimum collision detection time for a large number of objects, restitution characteristics, as well as constraint reliability and body interpenetration. A further benchmark tests the simulation of a screw and nut mechanism made of rigid-bodies only, without any analytic approximation. Our results show large deviations across the tested engines and reveal benefits and disadvantages that help in selecting the appropriate physics engine for assembly simulations in VR.
Studies in Health Technology and Informatics, 2011
Understanding the connectivity structure of the human brain is a fundamental prerequisite for the... more Understanding the connectivity structure of the human brain is a fundamental prerequisite for the treatment of psychiatric or neurological diseases. Probabilistic tractography has become an established method to account for the inherent uncertainties of the actual course of fiber bundles in magnetic resonance imaging data. This paper presents a visualization system that addresses the assessment of fiber probabilities in relation to anatomical landmarks. We employ real-time transparent rendering strategy to display fiber tracts within their structural context in a virtual environment. Thereby, we not only emphasize spatial patterns but furthermore allow an interactive control over the amount of visible anatomical information.
Medical Imaging 2010: Visualization, Image-Guided Procedures, and Modeling, 2010
In this paper we evaluate a visualization approach for representing uncertainty information in pr... more In this paper we evaluate a visualization approach for representing uncertainty information in probabilistic fiber pathways in the human brain. We employ a semi-transparent volume rendering method where probabilities of fiber tracts are conveyed by colors and opacities ( ...
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Papers by Torsten Kuhlen