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Eurographics/IEEE VGTC Symposium on Point-Based graphics, 2005

作者： Krüger, Jens Schneider, Jens Westermann, Rüdiger Computer Graphics and Visualization Group Technical University Munich Germany

ISBN: (纸本)3905673207

In this paper we present a compression scheme for large point scans including per-point normals. For the encoding of such scans we introduce a particular type of closest sphere packing grids, the hexagonal close packing (HCP). HCP grids provide a structure for an optimal packing of 3D space, and for a given sampling error they result in a minimal number of cells if geometry is sampled into these grids. To compress the data, we extract linear sequences (runs) of filled cells in HCP grids. The problem of determining optimal runs is turned into a graph theoretical one. Point positions and normals in these runs are incrementally encoded. At a grid spacing close to the point sampling distance, the compression scheme only requires slightly more than 3 bits per point position. Incrementally encoded per-point normals are quantized at high fidelity using only 5 bits per normal (see Figure 1). The compressed data stream can be decoded in the graphics processing unit (GPU). Decoded point positions are saved in graphics memory, and they are then used on the GPU again to render point primitives. In this way we render gigantic point scans from their compressed representation in local GPU memory at interactive frame rates (see Figure 2). © The Eurographics Association 2005.

关键词： Image compression

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DUODECIM - a structure for point scan compression and rendering

DUODECIM - a structure for point scan compression and render...

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Eurographics/IEEE VGTC Symposium Proceedings on Point-Based graphics, PBG

作者： J. Kruger J. Schneider R. Westermann Computer Graphics and Visualization Group Technical University Munich Germany Computer Graphics and Visualization Group Technical University Munich

In this paper we present a compression scheme for large point scans including per-point normals. For the encoding of such scans we introduce a particular type of closest sphere packing grids, the hexagonal close packing (HCP). HCP grids provide a structure for an optimal packing of 3D space, and for a given sampling error they result in a minimal number of cells if geometry is sampled into these grids. To compress the data, we extract linear sequences (runs) of filled cells in HCP grids. The problem of determining optimal runs is turned into a graph theoretical one. Point positions and normals in these runs are incrementally encoded. At a grid spacing close to the point sampling distance, the compression scheme only requires slightly more than 3 bits per point position. Incrementally encoded per-point normals are quantized at high fidelity using only 5 bits per normal. The compressed data stream can be decoded in the graphics processing unit (GPU). Decoded point positions are saved in graphics memory, and they are then used on the GPU again to render point primitives. In this way we render gigantic point scans from their compressed representation in local GPU memory at interactive frame rates.

关键词： Rendering (computer graphics) computer graphics Decoding Central Processing Unit Hardware Displays Image coding Sampling methods Lenses visualization

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The application of GPU particle tracing to diffusion tensor field visualization

The application of GPU particle tracing to diffusion tensor ...

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IEEE Conference on visualization

作者： P. Kondratieva J. Kruger R. Westermann Computer Graphics and Visualization Group Technische Universität München Germany Computer Graphics and Visualization Group Technische Universität München

In this paper we introduce GPU particle tracing for the visualization of 3D diffusion tensor fields. For about half a million particles, reconstruction of diffusion directions from the tensor field, time integration and rendering can be done at interactive rates. Different visualization options like oriented particles of diffusion-dependent shape, stream lines or stream tubes facilitate the use of particle tracing for diffusion tensor visualization. The proposed methods provide efficient and intuitive means to show the dynamics in diffusion tensor fields, and they accommodate the exploration of the diffusion properties of biological tissue.

关键词： Tensile stress visualization Shape Application software computer graphics Biological tissues Anisotropic magnetoresistance Aerodynamics Biology computing Biomedical imaging

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visualization for validation and improvement of three-dimensional segmentation algorithms

Visualization for validation and improvement of three-dimens...

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7th Joint Eurographics - IEEE VGTC Symposium on visualization, VisSym 2005

作者： Weber, G.H. Luengo Hendriks, C.L. Keränen, S.V.E. Dillard, S.E. Ju, D.Y. Sudar, D. Hamann, B. Berkeley Drosophila Transcription Network Project Visualization and Computer Graphics Research Group Institute for Data Analysis and Visualization University of California Davis One Shields Avenue DavisCA95616 United States Genomics and Life Sciences Division Lawrence Berkeley National Laboratory One Cyclotron Road BerkeleyCA94720 United States

ISBN: (纸本)3905673193

The Berkeley Drosophila Transcription Network Project (BDTNP) is developing a suite of methods that will allow a quantitative description and analysis of three dimensional (3D) gene expression patterns in an animal with cellular resolution. An important component of this approach are algorithms that segment 3D images of an organism into individual nuclei and cells and measure relative levels of gene expression. As part of the BDTNP, we are developing tools for interactive visualization, control, and verification of these algorithms. Here we present a volume visualization prototype system that, combined with user interaction tools, supports validation and quantitative determination of the accuracy of nuclear segmentation. visualizations of nuclei are combined with information obtained from a nuclear segmentation mask, supporting the comparison of raw data and its segmentation. It is possible to select individual nuclei interactively in a volume rendered image and identify incorrectly segmented objects. Integration with segmentation algorithms, implemented in MATLAB, makes it possible to modify a segmentation based on visual examination and obtain additional information about incorrectly segmented objects. This work has already led to significant improvements in segmentation accuracy and opens the way to enhanced analysis of images of complex animal morphologies. © The Eurographics Association 2005.

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GPU-PIV

GPU-PIV

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Vision, Modeling and visualization 2004, VMV 2004

作者： Schiwietz, Thomas Westermann, Rüdiger Siemens Corporate Research Inc. 755 College Road East PrincetonNJ08540 United States Technische Universität München Institut für Informatik Computer Graphics and Visualization Group Boltzmannstr. 3 Garching85748 Germany

ISBN: (纸本)3898380580

Digital Particle Image Velocimetry (PIV) is an optical technique used to measure the velocity of seeded particles in real flow. A CCD camera captures the flow field twice under exposure to a short duration laser flash. Recorded image pairs are cross-correlated to extract velocity information from these records. Time resolved PIV technology can capture images with some hundreds of frames per second. In this paper, we present a PIV-system that implements vector field reconstruction and visualization on programmable graphics processing units (GPUs) thus providing a high-speed back-end for time resolved PIV technology. We propose an efficient FFT implementation on such hardware, which is used to cross-correlate multiple pairs of interrogation windows. To visualize extracted vector fields we employ functionality to create and to render geometry data on the GPU. In this way, not only can any data transfer between the CPU and the GPU be avoided, but spatial information derived from PIV as well as the time history of points in the flow can be combined instantaneously.

关键词： graphics processing unit

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Compression domain volume rendering

Compression domain volume rendering

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IEEE Conference on visualization

作者： J. Schneider R. Westermann Computer Graphics and Visualization Group Technical University Munich Germany

A survey of graphics developers on the issue of texture mapping hardware for volume rendering would most likely find that the vast majority of them view limited texture memory as one of the most serious drawbacks of an otherwise fine technology. In this paper, we propose a compression scheme for static and time-varying volumetric data sets based on vector quantization that allows us to circumvent this limitation. We describe a hierarchical quantization scheme that is based on a multiresolution covariance analysis of the original field. This allows for the efficient encoding of large-scale data sets, yet providing a mechanism to exploit temporal coherence in non-stationary fields. We show, that decoding and rendering the compressed data stream can be done on the graphics chip using programmable hardware. In this way, data transfer between the CPU and the graphics processing unit (GPU) can be minimized thus enabling flexible and memory efficient real-time rendering options. We demonstrate the effectiveness of our approach by demonstrating interactive renditions of Gigabyte data sets at reasonable fidelity on commodity graphics hardware.

关键词： Rendering (computer graphics) computer graphics Hardware Vector quantization Data visualization Large-scale systems Decoding Central Processing Unit Shock waves Encoding

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Acceleration techniques for GPU-based volume rendering

Acceleration techniques for GPU-based volume rendering

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IEEE Conference on visualization

作者： J. Kruger R. Westermann Computer Graphics and Visualization Group Technical University Munich Germany

Nowadays, direct volume rendering via 3D textures has positioned itself as an efficient tool for the display and visual analysis of volumetric scalar fields. It is commonly accepted, that for reasonably sized data sets appropriate quality at interactive rates can be achieved by means of this technique. However, despite these benefits one important issue has received little attention throughout the ongoing discussion of texture based volume rendering: the integration of acceleration techniques to reduce per-fragment operations. In this paper, we address the integration of early ray termination and empty-space skipping into texture based volume rendering on graphical processing units (GPU). Therefore, we describe volume ray-casting on programmable graphics hardware as an alternative to object-order approaches. We exploit the early z-test to terminate fragment processing once sufficient opacity has been accumulated, and to skip empty space along the rays of sight. We demonstrate performance gains up to a factor of 3 for typical renditions of volumetric data sets on the ATI 9700 graphics card.

关键词： Acceleration Rendering (computer graphics) Hardware computer graphics Sampling methods Data visualization Three dimensional displays computer displays Performance gain Chromium

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MoireGraphs: Radial focus+context visualization and interaction for graphs with visual nodes

MoireGraphs: Radial focus+context visualization and interact...

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9th Annual IEEE Symposium on Information visualization, InfoVis 2003

作者： Jankun-Kelly, T.J. Ma, Kwan-Liu Department of Computer Science and Engineering Mississippi State University MS 39762 United States Visualization and Graphics Research Group Department of Computer Science University of California Davis CA 95616 United States

ISBN: (纸本)0780381548

Graph and tree visualization techniques enable interactive exploration of complex relations while communicating topology. However, most existing techniques have not been designed for situations where visual information such as images is also present at each node and must be displayed. This paper presents MoireGraphs to address this need. MoireGraphs combine a new focus+context radial graph layout with a suite of interaction techniques (focus strength changing, radial rotation, level highlighting, secondary foci, animated transitions and node information) to assist in the exploration of graphs with visual nodes. The method is scalable to hundreds of displayed visual nodes. © 2003 IEEE.

关键词： visualization

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MoireGraphs: radial focus+context visualization and interaction for graphs with visual nodes

MoireGraphs: radial focus+context visualization and interact...

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IEEE Symposium on Information visualization (INFOVIS)

作者： T.J. Jankun-Kelly Kwan-Liu Ma Department of Computer Science and Engineering Mississippi State University MS USA Visualization and Graphics Research Group Department of Computer Science University of California Davis CA USA

关键词： Focusing Tree graphs Topology Geometry Layout computer graphics Displays Animation Data visualization computer science

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Remote computing environment compensating for brain shift

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computer Aided Surgery 2003年第4期8卷 169-179页

作者： Hastreiter, Peter Engel, Klaus Soza, Grzegorz Wolf, Matthias Ganslandt, Oliver Fahlbusch, Rudolf Greiner, Gnther Ximsky, Christopher Department of Neurosurgery Neurocenter Friedrich Alexander University of Erlangen-Nuremberg D-91054 Erlangen Schwabachanlage 6. Germany Computer Graphics Group University of Erlangen-Nuremberg Erlangen Germany Visualization and Interactive Systems Group University of Stuttgart Erlangen Germany Knowledge Processing Group Bavarian Research Center for Knowledge-Based Systems Erlangen Germany

Objective: Anatomical and functional image data become invalid during an operation due to brain shift. Compensation is achieved by using intraoperative imaging to update anatomical information. To accelerate the registration and visualization of pre- and intraoperative image data, the presented work focuses on remote computing capabilities. The underlying framework efficiently combines local desktop computers and remote high-end graphics workstations exploiting expensive hardware. Methods: By performing all computations on the remote computer, the MR volumes are rigidly aligned via voxel-based registration. Using graphics hardware for acceleration, all interpolation operations are performed with 3D texture-mapping hardware. A new approach then transforms functional markers from preoperative measurements to the intraoperative situation using an automatic tracking algorithm to identify corresponding sulci. Communicating Java viewers are suggested for analyzing the results interactively on a local computer, with all calculations being performed exclusively on the remote computer. Results: The suggested approach was successfully applied in S cases using MR data containing functional markers of MEG and fMRI measurements identifying eloquent brain areas. Remote large-scale graphics hardware was thereby efficiently made available for fast registration and interactive direct volume rendering in neurosurgery. Conclusion: Overall, the presented framework demonstrates efficient access of expensive high- end hardware remotely controlled by thin clients, and further emphasizes the need to compensate for brain shift in functional neuronavigation. © 2003 Informa UK Ltd All rights reserved.

关键词： 3D visualization brain shift registration remote computing

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