The Experts below are selected from a list of 23511 Experts worldwide ranked by ideXlab platform
Thomas Ertl - One of the best experts on this subject based on the ideXlab platform.
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Spectral Volume Rendering using GPU-based raycasting
The Visual Computer, 2006Co-Authors: Magnus Strengert, Thomas Klein, Ralf P. Botchen, S. Stegmaier, Min Chen, Thomas ErtlAbstract:Traditional Volume Rendering does not incorporate a number of optical properties that are typically observed for semi-transparent materials, such as glass or water, in the real world. Therefore, we have extended GPU-based raycasting to spectral Volume Rendering based on the Kubelka–Munk theory for light propagation in parallel colorant layers of a turbid medium. This allows us to demonstrate the effects of selective absorption and dispersion in refractive materials, by generating Volume Renderings using real physical optical properties. We show that this extended Volume Rendering technique can be easily incorporated into a flexible framework for GPU-based Volume raycasting. Our implementation shows a promising performance for a number of real data sets. In particular, we obtain up to 100 times the performance of a comparable CPU implementation.
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The Visualization Handbook - 10 – Pre-Integrated Volume Rendering
Visualization Handbook, 2005Co-Authors: Martin Kraus, Thomas ErtlAbstract:The basic idea of pre-integrated Volume Rendering is the precomputation of the parts of the Volume Rendering integral. In this sense, it is similar to Volume Rendering using splatting and even more similar to the accelerated evaluation of the Volume Rendering integral within a tetrahedron. However, pre-integrated Volume Rendering is a more general concept that can be applied to many Volume Rendering algorithms and supports several different Rendering techniques. This chapter begins with describing the foundation of pre-integrated Volume Rendering—that is, pre-integrated classification, and discusses its relation to the Volume Rendering integral and its numerical evaluation. Pre-integrated classification is not restricted to a particular Volume Rendering algorithm; rather, it may replace the post-classification step of various algorithms as demonstrated by several publications in recent years. The chapter also attempts to give an overview of the literature on pre-integrated Volume Rendering algorithms.
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Direct Volume Rendering in OpenSG
Computers & Graphics, 2004Co-Authors: Manfred Weiler, Thomas Klein, Thomas ErtlAbstract:Abstract We present a Volume Rendering framework based on the OpenSG scene graph API. The framework defines Volumetric objects that can be included anywhere into an OpenSG scene graph; this allows to easily combine them with polygonally defined objects. The Rendering is performed via texture-based Volume Rendering algorithms based on either two-dimensional or three-dimensional texture maps. The primary background of our framework is scientific visualization of Volumetric data from sensoric measurements or simulations. Additionally, it also allows to enrich OpenSG scenes with Volumetric effects like fog or clouds. Our framework consists of only a few abstract objects with a plain interface for application developers, but also provides extensibility by applying a flexible shader concept. The shaders also allow to easily integrate new visualization algorithms, e.g. that utilize the features of upcoming graphics chip generations.
Arie E. Kaufman - One of the best experts on this subject based on the ideXlab platform.
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7 overview of Volume Rendering
The Visualization Handbook, 2005Co-Authors: Arie E. Kaufman, Klaus MuellerAbstract:Volume visualization is a method of extracting meaningful information from Volumetric data using interactive graphics and imaging. It is concerned with Volume data representation, modeling, manipulation, and Rendering. Volume data are 3D (possibly time-varying) entities that may have information inside them, may not consist of tangible surfaces and edges, or may be too voluminous to be represented geometrically. They are obtained by sampling, simulation, or modeling techniques. When Volumetric data are visualized using a surface-Rendering technique, a dimension of information is essentially lost. In response to this, Volume Rendering techniques were developed that attempt to capture the entire 3D data in a single 2D image. Volume Rendering conveys more information than surface-rendered images but at the cost of increased algorithm complexity and consequently increased Rendering times. To improve interactivity in Volume Rendering, many optimization methods both for software and graphics-accelerator implementations as well as several special-purpose Volume Rendering machines have been developed.
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The Visualization Handbook - 7 – Overview of Volume Rendering
Visualization Handbook, 2005Co-Authors: Arie E. Kaufman, Klaus MuellerAbstract:Volume visualization is a method of extracting meaningful information from Volumetric data using interactive graphics and imaging. It is concerned with Volume data representation, modeling, manipulation, and Rendering. Volume data are 3D (possibly time-varying) entities that may have information inside them, may not consist of tangible surfaces and edges, or may be too voluminous to be represented geometrically. They are obtained by sampling, simulation, or modeling techniques. When Volumetric data are visualized using a surface-Rendering technique, a dimension of information is essentially lost. In response to this, Volume Rendering techniques were developed that attempt to capture the entire 3D data in a single 2D image. Volume Rendering conveys more information than surface-rendered images but at the cost of increased algorithm complexity and consequently increased Rendering times. To improve interactivity in Volume Rendering, many optimization methods both for software and graphics-accelerator implementations as well as several special-purpose Volume Rendering machines have been developed.
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Graphics Hardware - Squeeze: numerical-precision-optimized Volume Rendering
Proceedings of the ACM SIGGRAPH EUROGRAPHICS conference on Graphics hardware - HWWS '04, 2004Co-Authors: Ingmar Bitter, Klaus Mueller, Neophytos Neophytou, Arie E. KaufmanAbstract:This paper discusses how to squeeze Volume Rendering into as few bits per operation as possible while still retaining excellent image quality. For each of the typical Volume Rendering pipeline stages in texture map Volume Rendering, ray casting and splatting we provide a quantitative analysis of the theoretical and practical limits for the required bit precision for computation and storage. Applying this analysis to any Volume Rendering implementation can balance the internal precisions based on the desired final output precision and can result in significant speedups and reduced memory footprint.
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Image-based Volume Rendering
1999Co-Authors: Arie E. Kaufman, Baoquan ChenAbstract:Volume Rendering, a technique for visualizing 3D arrays of sampled data, is computationally very expensive. Interactive Volume Rendering of large Volumes (over 10243) is in demand for such applications as biomedical simulation and geoscience. Existing software optimizations can barely meet the challenge of today's increasingly large datasets. Even the fastest workstations equipped with special hardware are quickly overwhelmed. So far, none of the current special-purpose Volume Rendering hardware designs achieve real-time frame rate for large Volumes at an acceptable hardware cost. In this dissertation, we propose an image-based framework which avails the coherence between neighboring frames during navigation of a Volume dataset. The previously fully Volume rendered view is cached as a keyview or keyframe. When generating the current novel view, instead of ray-casting the whole image, rays are cast only through those pixels which represent previously hidden objects. When the novel view camera moves only slightly away from that of keyview, the ray-cast pixels occupy only a small percent of the current view. Consequently, this gives us potential for vast speedup over traditional Volume Rendering. The rest of the novel view is generated directly from the keyview through inexpensive image transformation. To achieve this, we first construct a geometric iso-surface model from the Volume, where the iso-value is deducted from the input transfer function. We further texture-map the keyview onto the constructed geometric model through projective texture mapping and then project it to the novel view. We have explored separate algorithms optimized for several stages of the framework: an algorithm for generating levels-of-detail representation of regular Volumes—for efficient and levels-of-detail iso-surface extraction—and two algorithms for high quality and efficient texture mapping featuring backward and forward processing orders. To accelerate the Volume Rendering of keyview, we have developed a group of methods for decomposing 3D Volume rotation into shear transformations which lend themselves to a feasible hardware or parallel implementation. Even though these algorithms are designed within this framework, we have demonstrated that they can be extended to serve other numerous general applications. We have applied our framework to several practical navigation systems. We have achieved an average of a magnitude speedup over that of traditional Volume Rendering and obtained an interactive frame rate on a case study of a virtual colon navigation of a patient's 5123 colon data. We have also extended the framework to interactive Rendering of other data types, such as height field terrain and photograph sequence, and demonstrated the effectiveness of these extensions.
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PVR: high-performance Volume Rendering
IEEE Computational Science and Engineering, 1996Co-Authors: Cláudio T. Silva, Arie E. Kaufman, C. PavlakosAbstract:Traditional Volume Rendering methods are too slow to provide interactive visualization, especially for large 3D data sets. The PVR (parallel Volume Rendering) system implements parallel Volume Rendering techniques that speed up the visualization process. Moreover, it helps computational scientists, engineers, and physicians to more effectively apply Volume Rendering to visualization tasks. The authors describe the PVR system that they have developed in a collaboration between the State University of New York at Stony Brook and Sandia National Laboratories. PVR is an attempt to provide an easy-to-use portable system for high performance visualization with the speed required for interactivity and steering. The current version of PVR consists of about 25000 lines of C and Tcl/Tk code. It has been used at Stony Brook, Sandia, and Brookhaven National Labs to visualize large data sets for over a year.
Martin Kraus - One of the best experts on this subject based on the ideXlab platform.
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IEEE Visualization - Scale-invariant Volume Rendering
IEEE Visualization 2005 - (VIS'05), 2005Co-Authors: Martin KrausAbstract:As standard Volume Rendering is based on an integral in physical space (or "coordinate space"), it is inherently dependent on the scaling of this space. Although this dependency is appropriate for the realistic Rendering of semitransparent Volumetric objects, it has several unpleasant consequences for Volume visualization. In order to overcome these disadvantages, a new variant of the Volume Rendering integral is proposed, which is defined in data space instead of physical space. Apart from achieving scale invariance, this new method supports the Rendering of isosurfaces of uniform opacity and color, independently of the local gradient or" the visualized scalar field. Moreover, it reveals certain structures in scalar fields even with constant transfer functions. Furthermore, it can be defined as the limit of infinitely many semitransparent isosurfaces, and is therefore based on an intuitive and at the same time precise definition. In addition to the discussion of these features of scale-invariant Volume Rendering, efficient adaptations of existing Volume Rendering algorithms and extensions for silhouette enhancement and local illumination by transmitted light are presented.
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The Visualization Handbook - 10 – Pre-Integrated Volume Rendering
Visualization Handbook, 2005Co-Authors: Martin Kraus, Thomas ErtlAbstract:The basic idea of pre-integrated Volume Rendering is the precomputation of the parts of the Volume Rendering integral. In this sense, it is similar to Volume Rendering using splatting and even more similar to the accelerated evaluation of the Volume Rendering integral within a tetrahedron. However, pre-integrated Volume Rendering is a more general concept that can be applied to many Volume Rendering algorithms and supports several different Rendering techniques. This chapter begins with describing the foundation of pre-integrated Volume Rendering—that is, pre-integrated classification, and discusses its relation to the Volume Rendering integral and its numerical evaluation. Pre-integrated classification is not restricted to a particular Volume Rendering algorithm; rather, it may replace the post-classification step of various algorithms as demonstrated by several publications in recent years. The chapter also attempts to give an overview of the literature on pre-integrated Volume Rendering algorithms.
R Westermann - One of the best experts on this subject based on the ideXlab platform.
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acceleration techniques for gpu based Volume Rendering
IEEE Visualization, 2003Co-Authors: Jens Kruger, R WestermannAbstract: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.
Roni Yagel - One of the best experts on this subject based on the ideXlab platform.
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Slice-Based Volume Rendering
1993Co-Authors: J. Edward Swan, Roni YagelAbstract:A current goal in Volume graphics is a Volume Rendering algorithm that provides an elegant and controllable tradeoff between image quality and Rendering speed. In this report we propose a slice-based Volume Rendering algorithm which attempts to address this goal. We describe both the basic algorithm and several ways that it can operate in an incremental and an adaptive manner.
