Results 1  10
of
30
Optical Models for Direct Volume Rendering
, 1995
"... This tutorial survey paper reviews several different models for light interaction with volume densities of absorbing, glowing, reflecting, and/or scattering material. They are, in order of increasing realism, absorption only, emission only, emission and absorption combined, single scattering of exte ..."
Abstract

Cited by 242 (6 self)
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This tutorial survey paper reviews several different models for light interaction with volume densities of absorbing, glowing, reflecting, and/or scattering material. They are, in order of increasing realism, absorption only, emission only, emission and absorption combined, single scattering of external illumination without shadows, single scattering with shadows, and multiple scattering. For each model I give the physical assumptions, describe the applications for which it is appropriate, derive the differential or integral equations for light transport, present calculations methods for solving them, and show output images for a data set representing a cloud. Special attention is given to calculation methods for the multiple scattering model.
Volume Illustration: NonPhotorealistic Rendering of Volume Models
 IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS
, 2001
"... Accurately and automatically conveying the structure of a volume model is a problem not fully solved by existing volume rendering approaches. Physicsbased volume rendering approaches create images which may match the appearance of translucent materials in nature, but may not embody important struct ..."
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Cited by 158 (14 self)
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Accurately and automatically conveying the structure of a volume model is a problem not fully solved by existing volume rendering approaches. Physicsbased volume rendering approaches create images which may match the appearance of translucent materials in nature, but may not embody important structural details. Transfer function approaches allow flexible design of the volume appearance, but generally require substantial hand tuning for each new data set in order to be effective. We introduce the volume illustration approach, combining the familiarity of a physicsbased illumination model with the ability to enhance important features using nonphotorealistic rendering techniques. Since features to be enhanced are defined on the basis of local volume characteristics rather than volume sample value, the application of volume illustration techniques requires less manual tuning than the design of a good transfer function. Volume illustration provides a flexible unified framework for enhancing structural perception of volume models through the amplification of features and the addition of illumination effects.
HardwareAccelerated Volume and Isosurface Rendering Based on CellProjection
, 2000
"... We present two beneficial rendering extensions to the Projected Tetrahedra (PT) algorithm by Shirley and Tuchman. These extensions are compatible with any cell sorting technique, for example the BSPXMPVO sorting algorithm for unstructured meshes. ..."
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Cited by 85 (13 self)
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We present two beneficial rendering extensions to the Projected Tetrahedra (PT) algorithm by Shirley and Tuchman. These extensions are compatible with any cell sorting technique, for example the BSPXMPVO sorting algorithm for unstructured meshes.
Smart HardwareAccelerated Volume Rendering
, 2003
"... For volume rendering of regular grids the display of viewplane aligned slices has proven to yield both good quality and performance. In this paper we demonstrate how to merge the most important extensions of the original 3D slicing approach, namely the preintegration technique, volumetric clippi ..."
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Cited by 73 (12 self)
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For volume rendering of regular grids the display of viewplane aligned slices has proven to yield both good quality and performance. In this paper we demonstrate how to merge the most important extensions of the original 3D slicing approach, namely the preintegration technique, volumetric clipping, and advanced lighting. Our approach allows the suppression of clipping artifacts and achieves high quality while offering the flexibility to explore volume data sets interactively with arbitrary clip objects. We also outline how to utilize the proposed volumetric clipping approach for the display of segmented data sets. Moreover, we increase the rendering quality by implementing efficient oversampling with the pixel shader of consumer graphics accelerators. We give prove that at least 4times oversampling is needed to reconstruct the ray integral with sufficient accuracy even with preintegration.
HardwareBased Ray Casting for Tetrahedral Meshes
 In Proc. IEEE Visualization ’03
, 2003
"... Figure 1: All images show tetrahedral meshes consisting of 125K to 190K cells rendered with our hardwarebased ray casting algorithm. The algorithm exploits the programmable fragment unit of the ATI Radeon 9700 graphics chip and runs at several frames per second in a 512 × 512 viewport. The left ima ..."
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Cited by 67 (5 self)
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Figure 1: All images show tetrahedral meshes consisting of 125K to 190K cells rendered with our hardwarebased ray casting algorithm. The algorithm exploits the programmable fragment unit of the ATI Radeon 9700 graphics chip and runs at several frames per second in a 512 × 512 viewport. The left image shows multiple shaded isosurfaces, the middle and right images are rendered with a full densityemitter model. We present the first implementation of a volume ray casting algorithm for tetrahedral meshes running on offtheshelf programmable graphics hardware. Our implementation avoids the memory transfer bottleneck of the graphics bus since the complete mesh data is stored in the local memory of the graphics adapter and all computations, in particular ray traversal and ray integration, are performed by the graphics processing unit. Analogously to other ray casting algorithms, our algorithm does not require an expensive cell sorting. Provided that the graphics adapter offers enough texture memory, our implementation performs comparable to the fastest published volume rendering algorithms for unstructured meshes. Our approach works with cyclic and/or nonconvex meshes and supports early ray termination. Accurate ray integration is guaranteed by applying preintegrated volume rendering. In order to achieve almost interactive modifications of transfer functions, we propose a new method for computing threedimensional preintegration tables.
Sorting and Hardware Assisted Rendering for Volume Visualization
 Symposium on Volume Visualization
, 1994
"... We present some techniques for volume rendering unstructured data. Colors and opacities are interpolated between vertices using hardware assisted texture mapping. We also present an O(n 2 ) method for sorting n arbitrarily shaped convex polyhedra prior to visualization. It generalizes the Newel ..."
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Cited by 66 (6 self)
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We present some techniques for volume rendering unstructured data. Colors and opacities are interpolated between vertices using hardware assisted texture mapping. We also present an O(n 2 ) method for sorting n arbitrarily shaped convex polyhedra prior to visualization. It generalizes the Newell, Newell and Sancha sort for polygons to 3D volume elements. Introduction Tuchman, without artifacts due to linear approximation of the nonlinear opacity effects. This project grew out of the need to visualize unstructured meshed vector fields such as those found in existing finite element modeling code. Some volume rendering applications do not require more than one color. However, we have developed a visualization tool for rendering multicolored elements, such as colored flow volumes in a vector field, using an implementation of the ShirleyTuchman [1] algorithm. While monochromatic elements can be composited in any order as shown by [2], data sets containing many colors must be com...
Efficient Light Propagation for Multiple Anisotropic Volume Scattering
 In Proceedings of the 5th Eurographics Workshop on Rendering
, 1994
"... Realistic rendering of participating media like clouds requires multiple anisotropic light scattering. This paper presents a propagation approximation for light scattered into M direction bins, which reduces the "ray effect" problem in the traditional "discrete ordinates" method. For a regular grid ..."
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Cited by 65 (5 self)
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Realistic rendering of participating media like clouds requires multiple anisotropic light scattering. This paper presents a propagation approximation for light scattered into M direction bins, which reduces the "ray effect" problem in the traditional "discrete ordinates" method. For a regular grid volume of n 3 elements, it takes O(M n 3 log n + M 2 n 3 ) time and O(M n 3 + M 2 ) space. This document is reprinted from the proceedings of the Fifth Eurographics Workshop on Rendering, Darmstadt, Germany, June 13  15, 1994 1. Introduction To render realistic images of clouds, one must take into account absorption and multiple scattering of incoming illumination. In addition, to produce the bright edges surrounding a cloud when the sun is behind it, one must account for the anisotropic, mainly forward, scattering of light from the water droplets. In 1984, Jim Kajiya and Brian Von Herzen [Kaj84] proposed two methods for rendering clouds. The first was the twopass "slab" me...
A High Accuracy Volume Renderer for Unstructured Data
 IEEE Transactions on Visualization and Computer Graphics
, 1998
"... This paper describes a volume rendering system for unstructured data, especially finite element data, that creates images with very high accuracy. The system will currently handle meshes whose cells are either linear or quadratic tetrahedra. Compromises or approximations are not introduced for the s ..."
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Cited by 52 (6 self)
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This paper describes a volume rendering system for unstructured data, especially finite element data, that creates images with very high accuracy. The system will currently handle meshes whose cells are either linear or quadratic tetrahedra. Compromises or approximations are not introduced for the sake of efficiency. Whenever possible, exact mathematical solutions for the radiance integrals involved and for interpolation are used. The system will also handle meshes with mixed cell types: tetrahedra, bricks, prisms, wedges, and pyramids, but not with high accuracy. Accurate semitransparent shaded isosurfaces may be embedded in the volume rendering. For very small cells, subpixel accumulation by splatting is used to avoid sampling error. A revision to an existing accurate visibility ordering algorithm is described which includes a correction and a method for dramatically increasing its efficiency. Finally, hardware assisted projection and compositing are extended from tetrahedra to arbit...
Tetrahedral projection using vertex shaders
 IEEE Symposium on Volume Visualization and Graphics
, 2002
"... Sandia National Laboratories* Projective methods for volume rendering currently represent the best approach for interactive visualization of unstructured data sets. We present a technique for tetrahedral projection using the programmable vertex shaders on current generation commodity graphics cards. ..."
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Cited by 40 (1 self)
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Sandia National Laboratories* Projective methods for volume rendering currently represent the best approach for interactive visualization of unstructured data sets. We present a technique for tetrahedral projection using the programmable vertex shaders on current generation commodity graphics cards. The technique is based on Shirley and Tuchman’s Projected Tetrahedra (PT) algorithm and allows tetrahedral elements to be volume scan converted within the graphics processing unit. Our technique requires no preprocessing of the data and no additional data structures. Our initial implementation allows interactive viewing of large unstructured datasets on a desktop personal computer.
Gaussian transfer functions for multifield volume visualization
 In IEEE Visualization
, 2003
"... Volume rendering is a flexible technique for visualizing dense 3D volumetric datasets. A central element of volume rendering is the conversion between data values and observable quantities such as color and opacity. This process is usually realized through the use of transfer functions that are prec ..."
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Cited by 31 (6 self)
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Volume rendering is a flexible technique for visualizing dense 3D volumetric datasets. A central element of volume rendering is the conversion between data values and observable quantities such as color and opacity. This process is usually realized through the use of transfer functions that are precomputed and stored in lookup tables. For multidimensional transfer functions applied to multivariate data, these lookup tables become prohibitively large. We propose the direct evaluation of a particular type of transfer functions based on a sum of Gaussians. Because of their simple form (in terms of number of parameters), these functions and their analytic integrals along line segments can be evaluated efficiently on current graphics hardware, obviating the need for precomputed lookup tables. We have adopted these transfer functions because they are well suited for classification based on a unique combination of multiple data values that localize features in the transfer function domain. We apply this technique to the visualization of several multivariate datasets (CT, cryosection) that are difficult to classify and render accurately at interactive rates using traditional approaches.