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74
Differential Volume Rendering: A Fast Volume Visualization Technique for Flow Animation
, 1994
"... We present a direct volume rendering algorithm to speed up volume animation for flow visualizations. Data coherency between consecutive simulation time steps is used to avoid casting rays from those pixels retaining color values assigned to the previous image. The algorithm calculates the differenti ..."
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Cited by 47 (7 self)
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We present a direct volume rendering algorithm to speed up volume animation for flow visualizations. Data coherency between consecutive simulation time steps is used to avoid casting rays from those pixels retaining color values assigned to the previous image. The algorithm calculates the differential information among a sequence of 3D volumetric simulation data. At each time step the differential information is used to compute the locations of pixels that need updating and a raycasting method is utilized to produce the updated image. We illustrate the utility and speed of the differential volume rendering algorithm with simulation data from computational bioelectric and fluid dynamics applications. We can achieve considerable diskspace savings and nearly realtime rendering of 3D flows using lowcost, single processor workstations* for models which contain hundreds of thousands of data points.
The Multilevel Finite Element Method for Adaptive Mesh Optimization and Visualization of Volume Data
 In Proceedings Visualization
, 1997
"... Multilevel representations and mesh reduction techniques have been used for accelerating the processing and the rendering of large datasets representing scalar or vector valued functions defined on complex 2 or 3 dimensional meshes. We present a method based on finite element approximations which co ..."
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Cited by 46 (5 self)
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Multilevel representations and mesh reduction techniques have been used for accelerating the processing and the rendering of large datasets representing scalar or vector valued functions defined on complex 2 or 3 dimensional meshes. We present a method based on finite element approximations which combines these two approaches in a new and unique way that is conceptually simple and theoretically sound. The main idea is to consider mesh reduction as an approximation problem in appropriate finite element spaces. Starting with a very coarse triangulation of the functional domain a hierarchy of highly nonuniform tetrahedral (or triangular in 2D) meshes is generated adaptively by local refinement. This process is driven by controlling the local error of the piecewise linear finite element approximation of the function on each mesh element. A reliable and efficient computation of the global approximation error combined with a multilevel preconditioned conjugate gradient solver are the key co...
Selective Pixel Transmission for Navigating in Remote Virtual Environments
 Proc. Eurographics’97
, 1997
"... This paper presents a technique to improve the performance of a walkthrough in remote virtual environments, where a scene is rendered jointly by the server and the client, in order to reduce the network requirements as much as possible. The client generates novel views by extrapolating a reference ..."
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Cited by 34 (3 self)
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This paper presents a technique to improve the performance of a walkthrough in remote virtual environments, where a scene is rendered jointly by the server and the client, in order to reduce the network requirements as much as possible. The client generates novel views by extrapolating a reference view based on the locally available geometric model, while the server transmits data necessary to prevent an accumulation of errors. Within this concept, we show that by transmitting only a selected subset of pixels, the quality of the extrapolated views can be improved while requiring less bandwidth. We focus on the selection process in which the visibility gaps between the reference view and novel view are detected, packed and transmitted compressed to the client.
A practical evaluation of popular volume rendering algorithms
 IN PROCEEDINGS OF THE 2000 IEEE SYMPOSIUM ON VOLUME VISUALIZATION
, 2000
"... This paper evaluates and compares four volume rendering algorithms that have become rather popular for rendering datasets described on uniform rectilinear grids: raycasting, splatting, shearwarp, and hardwareassisted 3D texturemapping. In order to assess both the strengths and the weaknesses of t ..."
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Cited by 31 (2 self)
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This paper evaluates and compares four volume rendering algorithms that have become rather popular for rendering datasets described on uniform rectilinear grids: raycasting, splatting, shearwarp, and hardwareassisted 3D texturemapping. In order to assess both the strengths and the weaknesses of these algorithms in a wide variety of scenarios, a set of reallife benchmark datasets with different characteristics was carefully selected. In the rendering, all algorithmindependent image synthesis parameters, such as viewing matrix, transfer functions, and optical model, were kept constant to enable a fair comparison of the rendering results. Both image quality and computational complexity were evaluated and compared, with the aim of providing both researchers and practitioners with guidelines on which algorithm is most suited in which scenario. Our analysis also indicates the current weaknesses in each algorithm’s pipeline, and possible solutions to these as well as pointers for future research are offered.
Accelerated Volume RayCasting using Texture Mapping
"... Acceleration techniques for volume raycasting are primarily based on precomputed data structures that allow one to efficiently traverse empty or homogeneous regions. In order to display volume data that successively undergoes color lookups, however, the data structures have to be rebuilt continuo ..."
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Cited by 25 (0 self)
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Acceleration techniques for volume raycasting are primarily based on precomputed data structures that allow one to efficiently traverse empty or homogeneous regions. In order to display volume data that successively undergoes color lookups, however, the data structures have to be rebuilt continuously. In this paper we propose a technique that circumvents this drawback using hardware accelerated texture mapping. In a first rendering pass we employ graphics hardware to interactively determine for each ray where the material is hit. In a second pass raycasting is performed, but ray traversal starts right in front of the previously determined regions. The algorithm enables interactive classification and it considerably accelerates the view dependent display of selected materials and surfaces from volume data. In contrast to other techniques that are solely based on texture mapping our approach requires less memory and accurately performs the composition of material contributions along the ray.
An Interactive Visualization and Navigation Tool for Medical Volume Data
 WSCG '98, The Sixth International Conference in Central Europe on Computer Graphics and Visualization '98, volume II
, 1998
"... Interactive direct volume rendering by hardware assisted 3D texture mapping has become a powerful visualization method in many different fields. However, to make this technique fully practicable convenient visualization options and data analysis tools have to be integrated. For example, direct rende ..."
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Cited by 25 (13 self)
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Interactive direct volume rendering by hardware assisted 3D texture mapping has become a powerful visualization method in many different fields. However, to make this technique fully practicable convenient visualization options and data analysis tools have to be integrated. For example, direct rendering of semitransparent volume objects with integrated display of lighted isosurfaces is one important challenge especially in medical applications. Furthermore, explicit use of multidimensional image processing operations often helps to optimize the exploration of the available data sets. On the other hand, only if interactive frame rates can be guaranteed, such visualization tools will be accepted in medical planing and surgery simulation systems. In this paper we propose a volume visualization tool for large scale medical volume data which takes advantage of hardware assisted 3D texture interpolation and convolution operations. We demonstrate how to use the 3D texture mapping capabilit...
MultiFrame Thrashless Ray Casting with Advancing RayFront
 In Proc. of Graphics Interfaces
, 1996
"... Coherency (data locality) is one of the most important factors that influences the performance of distributed ray tracing systems, especially when object dataflow approach is employed. The enormous cost associated with remote fetches must be reduced to improve the efficiency of the parallel renderer ..."
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Cited by 20 (4 self)
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Coherency (data locality) is one of the most important factors that influences the performance of distributed ray tracing systems, especially when object dataflow approach is employed. The enormous cost associated with remote fetches must be reduced to improve the efficiency of the parallel renderer. Objects once fetched should be maximally utilized before replacing them with other objects. In this paper, we describe a parallel volume ray caster that eliminates thrashing by efficiently advancing a rayfront in a fronttoback manner. The method adopts an imageorder approach, but capitalizes on the advantages of objectorder algorithms as well to almost eliminate the communication overheads. Unlike previous algorithms, we have successfully preserved the thrashless property across a number of incrementally changing screen positions also. The use of efficient data structures and object ordering scheme has enabled complete latency hiding of nonlocal objects. The sum total of all these re...
A Lipschitz Method for Accelerated Volume Rendering
, 1994
"... Interpolating discrete volume data into a continuous form adapts implicit surface techniques for rendering volumetric isosurfaces. One such algorithm uses the Lipschitz condition to create an octree representation that accelerates volume rendering. Furthermore, only one preprocessing step is needed ..."
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Cited by 19 (3 self)
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Interpolating discrete volume data into a continuous form adapts implicit surface techniques for rendering volumetric isosurfaces. One such algorithm uses the Lipschitz condition to create an octree representation that accelerates volume rendering. Furthermore, only one preprocessing step is needed to create the Lipschitzoctree representation that accelerates rendering of isosurfaces for any threshold value.
An AntiAliasing Technique for Splatting
, 1997
"... Splatting is a popular direct volume rendering algorithm. However, the algorithm does not correctly render cases where the volume sampling rate is higher than the image sampling rate (e.g. more than one voxel maps into a pixel). This situation arises with orthographic projections of highresolution ..."
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Cited by 17 (1 self)
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Splatting is a popular direct volume rendering algorithm. However, the algorithm does not correctly render cases where the volume sampling rate is higher than the image sampling rate (e.g. more than one voxel maps into a pixel). This situation arises with orthographic projections of highresolution volumes, as well as with perspective projections of volumes of any resolution. The result is potentially severe spatial and temporal aliasing artifacts. Some volume ray casting algorithms avoid these artifacts by employing reconstruction kernels which vary in width as rays diverge. Unlike ray casting algorithms, existing splatting algorithms to not have an equivalent mechanism for avoiding these artifacts. In this paper we propose such a mechanism, which delivers highquality splatted images and has the potential for a very efficient hardware implementation.
A spectral analysis of function composition and its implications for sampling in direct volume visualization
 IEEE TRANSACTIONS VISUALIZATION AND COMPUTER GRAPHICS
, 2006
"... In this paper we investigate the effects of function composition in the form g ( f(x)) = h(x) by means of a spectral analysis of h. We decompose the spectral description of h(x) into a scalar product of the spectral description of g(x) and a term that solely depends on f(x) and that is independent ..."
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Cited by 15 (4 self)
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In this paper we investigate the effects of function composition in the form g ( f(x)) = h(x) by means of a spectral analysis of h. We decompose the spectral description of h(x) into a scalar product of the spectral description of g(x) and a term that solely depends on f(x) and that is independent of g(x). We then use the method of stationary phase to derive the essential maximum frequency of g ( f(x)) bounding the main portion of the energy of its spectrum. This limit is the product of the maximum frequency of g(x) and the maximum derivative of f(x). This leads to a proper sampling of the composition h of the two functions g and f. We apply our theoretical results to a fundamental open problem in volume rendering—the proper sampling of the rendering integral after the application of a transfer function. In particular, we demonstrate how the sampling criterion can be incorporated in adaptive ray integration, visualization with multidimensional transfer functions, and preintegrated volume rendering.