Search Results

Now showing 1 - 10 of 29
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    Comparative Visualization of Instabilities in Crash-Worthiness Simulations
    (The Eurographics Association, 2001) Sommer, Ove; Ertl, Thomas; David S. Ebert and Jean M. Favre and Ronald Peikert
    Since crash-worthiness simulations get more and more important as part of the car development process in order to reduce the cost of development, enhance the product quality, and minimize the time-to-market, the reliability of the simulation results plays a decisive role concerning their significance. Recently the simulation departments of several automotive companies started investigating the quantity and reason for deviations during a number of simulation runs on the same input model. In this case study we discuss different measurements for instability and present a texture-based visualization method which allows the engineers to efficiently explore the simulation results by interactively hiding finite element structures with nearly constant crash performance. Furthermore, we describe those parts of our prototype which use a CORBA layer for providing the same view on a set of simulation results and allowing the visual comparison by using the marker functionality.
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    Interactive High-Quality Volume Rendering with Flexible Consumer Graphics Hardware
    (Eurographics Association, 2002) Engel, Klaus; Ertl, Thomas
    Recently, the classic rendering pipeline in 3D graphics hardware has become flexible by means of programmable geometry engines and rasterization units. This development is primarily driven by the mass market of computer games and entertainment software, whose demand for new special effects and more realistic 3D environments induced a reconsideration of the once static rendering pipeline. Besides the impact on visual scene complexity in computer games, these advances in flexibility provide an enormous potential for new volume rendering algorithms. Thereby, they make yet unseen quality as well as improved performance for scientific visualization possible and allow to visualize hidden features contained within volumetric data. The goal of this report is to deliver insight into the new possibilities that programmable state-of-the-art graphics hardware offers to the field of interactive, high-quality volume rendering. We cover different slicing approaches for texture-based volume rendering, non-polygonal iso-surfaces, dot-product shading, environment-map shading, shadows, pre- and post-classification, multi-dimensional classification, high-quality filtering, pre-integrated classification and pre-integrated volume rendering, large volume visualization and volumetric effects.
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    A Multiscale Approach to Integrated Volume Segmentation and Rendering
    (Blackwell Publishers Ltd and the Eurographics Association, 1997) Westermann, Rudiger; Ertl, Thomas
    A number of techniques have been proposed for rendering volumetric scalar data sets. Techniques have also been proposed for analyzing the three dimensional information contents of the underlying domain, but traditionally the data analysis part is left as a post-processing step which only involves the rendered two dimensional images. In this paper, we describe a visualization method for scalar volume data which integrates explicit knowledge of the underlying domain into the rendering process. The key of this approach lies in a hierarchical description of the discrete signal, which is decomposed into a sequence of multiscale representations. We describe a technique for the analysis of structures within the data. This allows for the segmentation and classification of the relevant features and can be used to improve their visual sensation. We also address the problem of accelerating the final rendering pass by integrating the extracted object space information into the ray traversal process.
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    Interactive Visualization with Programmable Graphics Hardware
    (Eurographics Association, 2002) Ertl, Thomas
    One of the main scientific goals of visualization is the development of algorithms and appropriate data models which facilitate interactive visual analysis and direct manipulation of the increasingly large data sets which result from simulations running on massive parallel computer systems, from measurements employing fast highresolution sensors, or from large databases and hierarchical information spaces. This task can only be achieved with the optimization of all stages of the visualization pipeline: filtering, compression, and feature extraction of the raw data sets, adaptive visualization mappings which allow the users to choose between speed and accuracy, and exploiting new graphics hardware features for fast and high-quality rendering. The recent introduction of advanced programmability in widely available graphics hardware has already led to impressive progress in the area of volume visualization. However, besides the acceleration of the final rendering, flexible graphics hardware is increasingly being used also for the mapping and filtering stages of the visualization pipeline, thus giving rise to new levels of interactivity in visualization applications. The talk will present recent results of applying programmable graphics hardware in various visualization algorithms covering volume data, flow data, terrains, NPR rendering, and distributed and remote applications.
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    Interactively Visualizing Procedurally Encoded Scalar Fields
    (The Eurographics Association, 2004) Jang, Yun; Weiler, Manfred; Hopf, Matthias; Huang, Jingshu; Ebert, David S.; Gaither, Kelly P.; Ertl, Thomas; Oliver Deussen and Charles Hansen and Daniel Keim and Dietmar Saupe
    While interactive visualization of rectilinear gridded volume data sets can now be accomplished using texture mapping hardware on commodity PCs, interactive rendering and exploration of large scattered or unstructured data sets is still a challenging problem. We have developed a new approach that allows the interactive rendering and navigation of procedurally-encoded 3D scalar fields by reconstructing these fields on PC class graphics processing units. Since the radial basis functions (RBFs) we use for encoding can provide a compact representation of volumetric scalar fields, the large grid/mesh traditionally needed for rendering is no longer required and ceases to be a data transfer and computational bottleneck during rendering. Our new approach will interactively render RBF encoded data obtained from arbitrary volume data sets, including both structured volume models and unstructured scattered volume models. This procedural reconstruction of large data sets is flexible, extensible, and can take advantage of the Moore's Law cubed increase in performance of graphics hardware.
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    Real-Time Advection and Volumetric Illumination for the Visualization of 3D Unsteady Flow
    (The Eurographics Association, 2005) Weiskopf, Daniel; Schafhitzel, Tobias; Ertl, Thomas; Ken Brodlie and David Duke and Ken Joy
    This paper presents an interactive technique for the dense texture-based visualization of unsteady 3D flow, taking into account issues of computational efficiency and visual perception. High efficiency is achieved by a novel 3D GPU-based texture advection mechanism that implements logical 3D grid structures by physical memory in the form of 2D textures. This approach results in fast read and write access to physical memory, independent of GPU architecture. Slice-based direct volume rendering is used for the final display. A real-time computation of gradients is employed to achieve volume illumination. Perception-guided volume shading methods are included, such as halos, cool/warm shading, or color-based depth cueing. The problems of clutter and occlusion are addressed by supporting a volumetric importance function that enhances features of the flow and reduces visual complexity in less interesting regions.
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    A Simple and Flexible Volume Rendering Framework for Graphics-Hardware-based Raycasting
    (The Eurographics Association, 2005) Stegmaier, Simon; Strengert, Magnus; Klein, Thomas; Ertl, Thomas; Klaus Mueller and Thomas Ertl and Eduard Groeller
    In this work we present a flexible framework for GPU-based volume rendering. The framework is based on a single pass volume raycasting approach and is easily extensible in terms of new shader functionality. We demonstrate the flexibility of our system by means of a number of high-quality standard and non-standard volume rendering techniques. Our implementation shows a promising performance in a number of benchmarks while producing images of higher accuracy than obtained by standard pre-integrated slice-based volume rendering.
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    Shadow Mapping Based on Dual Depth Layers
    (Eurographics Association, 2003) Weiskopf, Daniel; Ertl, Thomas
    Shadow maps are a widely used means for the generation of shadows although they exhibit aliasing artifacts and problems of numerical precision. In this paper we extend the concept of a single shadow map by introducing dual shadow maps, which are based on the two depth layers that are closest to the light source. Our shadow algorithm takes into account these two depth values and computes an adaptive depth bias to achieve a robust determination of shadowed regions. Dual depth mapping only modifies the construction of the shadow map and can therefore be combined with other extensions such as filtering, perspective shadow maps, or adaptive shadow maps. Our approach can be mapped to graphics hardware for interactive applications and can also be used in high-quality software renderers.
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    GPU-Based Nonlinear Ray Tracing
    (The Eurographics Association and Blackwell Publishing, Inc, 2004) Weiskopf, Daniel; Schafhitzel, Tobias; Ertl, Thomas
    In this paper, we present a mapping of nonlinear ray tracing to the GPU which avoids any data transfer back to main memory. The rendering process consists of the following parts: ray setup according to the camera parameters, ray integration, ray-object intersection, and local illumination. Bent rays are approximated by polygonal lines that are represented by textures. Ray integration is based on an iterative numerical solution of ordinary differential equations whose initial values are determined during ray setup. To improve the rendering performance, we propose acceleration techniques such as early ray termination and adaptive ray integration. Finally, we discuss a variety of applications that range from the visualization of dynamical systems to the general relativistic visualization in astrophysics and the rendering of the continuous refraction in media with varying density.Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism
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    Hardware Accelerated Wavelet Transformations
    (The Eurographics Association, 2000) Hopf, Matthias; Ertl, Thomas; W. de Leeuw and R. van Liere
    Wavelets and related multiscale representations are important means for edge detection and processing as well as for segmentation and registration. Due to the computational complexity of these approaches no interactive visualization of the extraction process is possible nowadays. By using the hardware of modern graphics workstations for accelerating wavelet decomposition and reconstruction we realize a first important step for removing lags in the visualization cycle.