1,721,602 research outputs found
Interactive tracing of radio waves and neuronal fiber pathways for exploratory visualization in virtual reality
No full textExploratory visualization of physical simulations in virtual environments greatly benefits from interactively changing parameters with real-time feedback. The present thesis addresses two specific research questions by problem reformulation and implementation on the Graphics Processing Unit's many-core architecture towards a simulation and interaction in real-time: (1) simulating and manipulating wireless radio networks and (2) estimating and disambiguating neuronal fiber connectivity in the living human brain. This works assists in the exploratory scientific analysis by directly coupling simulation input and output with visual feedback and natural interaction via an interactive Virtual Reality (VR) interface. The user becomes an integral part of the workflow in order to observe computation results in real-time and to react appropriately. An interactive manipulation is enabled by decomposing and reformulating the domain specific algorithms into parallel sub tasks. Their scalability is demonstrated in the presence of a huge number of cores as available on current graphics hardware. This work uses VR interfaces to put the user in more control of the computing pipeline in order to exploit the full potential of a human-in-the-loop to see patterns and structures arise
Navigation in time-varying scientific data
No full textThe temporal resolution of today's simulated scientific data sets is constantly growing. Simulations spanning thousands of discrete time steps are common these days; simulations with a much higher resolution exist. The growing amount of discrete time steps leads to significant problems, particularly concerning the navigation through such data sets. This thesis presents a set of techniques that together enable an intuitive, interactive, and accurate navigation through time-varying scientific data. A time model that describes different time scales and their relations in scientific visualizations serves as a basis. Novel 3D interaction techniques for search and maneuver navigation tasks are developed and are evaluated in user studies. Based on initial user input, the temporal resolution of time-varying scientific data is adapted by a multi-objective optimization approach, which tries to combine conflicting analysis goals. In order to speed up the computation of time-varying visualizations during navigation, a remote parallel computation system using different user-centered scheduling strategies is presented. The developed approaches are evaluated using multiple large time-varying data sets from medicine, geosciences and flow mechanics. The heterogeneous techniques proposed - applied individually as well as in combination - enable or ease the analysis of large time-varying data in an interactive work process
Low latency technology for interactive virtual environments
No full textMinimizing system latency is a traditionally important topic for the development of multi-modal Virtual Environments (VE). Human perception thresholds have to be met in order to create immersive environments with a high degree of believability. The system latency has to be in the range of milliseconds, indicating the need for fast interfaces and low system overhead. This thesis provides a comprehensive approach to the creation of multi-modal VEs with high requirements on low latencies, abstract and flexible, yet real-time capable interfaces for device data handling and versatile application support mechanisms. In that sense it offers a stable software and conceptual basis for the development of appealing multi-modal environments. The “Virtueller Kopfhörer” (VirKopf) system is a representative of a demanding multi-modal environment that was developed as a joint research project between the Institute of Technical Acoustics and the VR Group at the Department of Computer Science at RWTH Aachen University. It features binaural acoustics, which enables the placing of virtual sounds at arbitrary 3-D positions within the scene, even very close to the user's head. Headphone-less reproduction is supported by dynamic crosstalk cancellation (CTC). The system is designed for immersive CAVE-like environments. As a cost for this comprehensive system, the requirements for a precise setup and accurate data processing have to be respected very carefully. For example, delivering the correct tracking data with a low latency is most crucial for the successful application of the dynamic CTC. By using CTC, a sweet spot is created, providing a correct sound field impression for the user. In a dynamic system, where the user is free to move arbitrarily, this sweet spot is constantly updated to the current position of the ears of the user, which in term is determined by a tracking device. Due to the discrete processing, a misalignment between the assumed and real position of the user's ears can occur. A misalignment between these positions of above 1 cm is enough to cause audible artefacts for the listener, disrupting the 3-D impression of the auralized scene. This is a severe constraint, as practically the runtime of the sound waves from the loudspeakers to the user's ears can take several milliseconds, and this can not be compensated by faster tracking hardware. Predictive tracking can be used to estimate a future position of the user's ears based on observations from the past. However, these algorithms can not forecast arbitrarily into the future and a low latency system support is a mandatory precondition for a successful application. Low latency processing is not only important for the VirKopf system, but a general requirement on VR software, especially for device and interaction handling. A versatile, flexible and runtime optimal VR device driver architecture is introduced. This architecture enables the parallel low-latency data access for multi-modal data streams and enhanced interaction algorithms as it supports driver-level histories. Additionally, the architecture suggests enhanced transformation and application stages which simplify the application development for the field of VR. The resulting misalignment of the estimation of the user's head in the virtual scene is lowered by an adaptive predictive tracking algorithm. The suggested solution features an on-line update strategy based solely on the local development of the tracking sensor's velocity. The coupling of a visual VR system with its acoustic counterpart as a network communication architecture is defined and its capabilities explained. The cost of end-to-end latency with respect to this audio-visual coupling architecture is inspected and discussed in detail. In addition to the optimized system behavior, an application architecture for multi-modal VEs is described. This approach models VEs as a collection of communicating agents, enabling the building of versatile interactive, multi-modal virtual worlds. A cluster rendering scheme based on a hybrid master-slave architecture is introduced. This approach is furthermore optimized for a minimal latency state processing from master to slave
Interactive tracing of radio waves and neuronal fiber pathways for exploratory visualization in virtual reality
No full textExploratory visualization of physical simulations in virtual environments greatly benefits from interactively changing parameters with real-time feedback. The present thesis addresses two specific research questions by problem reformulation and implementation on the Graphics Processing Unit's many-core architecture towards a simulation and interaction in real-time: (1) simulating and manipulating wireless radio networks and (2) estimating and disambiguating neuronal fiber connectivity in the living human brain. This works assists in the exploratory scientific analysis by directly coupling simulation input and output with visual feedback and natural interaction via an interactive Virtual Reality (VR) interface. The user becomes an integral part of the workflow in order to observe computation results in real-time and to react appropriately. An interactive manipulation is enabled by decomposing and reformulating the domain specific algorithms into parallel sub tasks. Their scalability is demonstrated in the presence of a huge number of cores as available on current graphics hardware. This work uses VR interfaces to put the user in more control of the computing pipeline in order to exploit the full potential of a human-in-the-loop to see patterns and structures arise
Low latency technology for interactive virtual environments
No full textMinimizing system latency is a traditionally important topic for the development of multi-modal Virtual Environments (VE). Human perception thresholds have to be met in order to create immersive environments with a high degree of believability. The system latency has to be in the range of milliseconds, indicating the need for fast interfaces and low system overhead. This thesis provides a comprehensive approach to the creation of multi-modal VEs with high requirements on low latencies, abstract and flexible, yet real-time capable interfaces for device data handling and versatile application support mechanisms. In that sense it offers a stable software and conceptual basis for the development of appealing multi-modal environments. The “Virtueller Kopfhörer” (VirKopf) system is a representative of a demanding multi-modal environment that was developed as a joint research project between the Institute of Technical Acoustics and the VR Group at the Department of Computer Science at RWTH Aachen University. It features binaural acoustics, which enables the placing of virtual sounds at arbitrary 3-D positions within the scene, even very close to the user's head. Headphone-less reproduction is supported by dynamic crosstalk cancellation (CTC). The system is designed for immersive CAVE-like environments. As a cost for this comprehensive system, the requirements for a precise setup and accurate data processing have to be respected very carefully. For example, delivering the correct tracking data with a low latency is most crucial for the successful application of the dynamic CTC. By using CTC, a sweet spot is created, providing a correct sound field impression for the user. In a dynamic system, where the user is free to move arbitrarily, this sweet spot is constantly updated to the current position of the ears of the user, which in term is determined by a tracking device. Due to the discrete processing, a misalignment between the assumed and real position of the user's ears can occur. A misalignment between these positions of above 1 cm is enough to cause audible artefacts for the listener, disrupting the 3-D impression of the auralized scene. This is a severe constraint, as practically the runtime of the sound waves from the loudspeakers to the user's ears can take several milliseconds, and this can not be compensated by faster tracking hardware. Predictive tracking can be used to estimate a future position of the user's ears based on observations from the past. However, these algorithms can not forecast arbitrarily into the future and a low latency system support is a mandatory precondition for a successful application. Low latency processing is not only important for the VirKopf system, but a general requirement on VR software, especially for device and interaction handling. A versatile, flexible and runtime optimal VR device driver architecture is introduced. This architecture enables the parallel low-latency data access for multi-modal data streams and enhanced interaction algorithms as it supports driver-level histories. Additionally, the architecture suggests enhanced transformation and application stages which simplify the application development for the field of VR. The resulting misalignment of the estimation of the user's head in the virtual scene is lowered by an adaptive predictive tracking algorithm. The suggested solution features an on-line update strategy based solely on the local development of the tracking sensor's velocity. The coupling of a visual VR system with its acoustic counterpart as a network communication architecture is defined and its capabilities explained. The cost of end-to-end latency with respect to this audio-visual coupling architecture is inspected and discussed in detail. In addition to the optimized system behavior, an application architecture for multi-modal VEs is described. This approach models VEs as a collection of communicating agents, enabling the building of versatile interactive, multi-modal virtual worlds. A cluster rendering scheme based on a hybrid master-slave architecture is introduced. This approach is furthermore optimized for a minimal latency state processing from master to slave
Bimanual interaction for medical virtual environments: palpation and needle intervention
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