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85
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.
Fast Algorithms for Volume Ray Tracing
, 1992
"... We examine various simple algorithms that exploit homogeneity and accumulated opacity for tracing rays through shaded volumes. Most of these methods have error criteria which allow them to trade quality for speed. The time vs. quality tradeoff for these adaptive methods is compared to fixed step mul ..."
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Cited by 107 (0 self)
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We examine various simple algorithms that exploit homogeneity and accumulated opacity for tracing rays through shaded volumes. Most of these methods have error criteria which allow them to trade quality for speed. The time vs. quality tradeoff for these adaptive methods is compared to fixed step multiresolution methods. These methods are also useful for general light transport in volumes. 1 Introduction We are interested in speeding volume ray tracing computations. We concentrate on the one dimensional problem of tracing a single ray, or computing the intensity at a point from a single direction. In addition to being the kernel of a simple volume ray tracer, this computation can be used to generate shadow volumes and as an element in more general light transport problems. Our data structures will be view independent to speed the production of animations of preshaded volumes and interactive viewing. In [11] Levoy introduced two key concepts which we will be expanding on: presence accel...
Direct Volume Rendering with Shading via ThreeDimensional Textures
, 1996
"... A new and easytoimplement method for direct volume rendering that uses 3D texture maps for acceleration, and incorporates directional lighting, is described. The implementation, called Voltx, produces highquality images at nearly interactive speeds on workstations with hardware support for three ..."
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Cited by 87 (1 self)
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A new and easytoimplement method for direct volume rendering that uses 3D texture maps for acceleration, and incorporates directional lighting, is described. The implementation, called Voltx, produces highquality images at nearly interactive speeds on workstations with hardware support for threedimensional texture maps. Previously reported methods did not incorporate a light model, and did not address issues of multiple texture maps for large volumes. Our research shows that these extensions impact performance by about a factor of ten. Voltx supports orthographic, perspective, and stereo views. This paper describes the theory and implementation of this technique, and compares it to the shearwarp factorization approach. A rectilinear data set is converted into a threedimensional texture map containing color and opacity information. Quantized normal vectors and a lookup table provide efficiency. A new tesselation of the sphere is described, which serves as the basis for normalvec...
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.
Hardware Assisted Volume Rendering of Unstructured Grids by Incremental Slicing
, 1996
"... Some of the more important research results in computational science rely on the use of simulation methods that operate on unstructured grids. However, these grids, composed of a set of convex polyhedra, introduce exceptional problems with respect to data visualization. Volume rendering techniques ..."
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Cited by 69 (0 self)
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Some of the more important research results in computational science rely on the use of simulation methods that operate on unstructured grids. However, these grids, composed of a set of convex polyhedra, introduce exceptional problems with respect to data visualization. Volume rendering techniques, originally developed to handle rectangular grids, show significant promise for general use with unstructured grids as well. The main disadvantage of this approach, compared to isosurfaces, particles or other visualization tools is its noninteractive performance. We describe an efficient method for rendering unstructured grids that is based on incremental slicing and hardware polygon rendering. For a given view direction, the grid vertices are transformed to image space using available graphics hardware. We then incrementally compute the 2D polygonmeshes that result from letting a set of equidistant planes, parallel to the screen plane, intersect (slice) the transformed grid. Final...
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...
Flow Volumes For Interactive Vector Field Visualization
, 1993
"... Flow volumes are the volumetric equivalent of stream lines. They provide more information about the vector field being visualized than do stream lines or ribbons. Presented is an efficient method for producing flow volumes, composed of transparently rendered tetrahedra, for use in an interactive sys ..."
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Cited by 62 (8 self)
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Flow volumes are the volumetric equivalent of stream lines. They provide more information about the vector field being visualized than do stream lines or ribbons. Presented is an efficient method for producing flow volumes, composed of transparently rendered tetrahedra, for use in an interactive system. The problems of rendering, subdivision, sorting,compositing artifacts, and user interaction are dealt with. Efficiency comes from rendering only the volume of the smoke, using hardware texturing and compositing.
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...
Direct Volume Rendering via 3D Textures
, 1994
"... The advent of very fast texture mapping hardware in modern graphics workstations has warranted research into rendering techniques that use texture mapping to full advantage. We have developed a new and easy to implement method for direct volume rendering that produces highquality images at speeds a ..."
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Cited by 50 (2 self)
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The advent of very fast texture mapping hardware in modern graphics workstations has warranted research into rendering techniques that use texture mapping to full advantage. We have developed a new and easy to implement method for direct volume rendering that produces highquality images at speeds approaching two orders of magnitude faster than existing techniques, on workstations with hardware support for threedimensional texture maps. A rectilinear data set is converted into a threedimensional texture map containing color and opacity information. In the rendering phase, the texture map is then applied to a stack of parallel planes, which effectively cut the texture into many slices. The slices are composited to form an image of the original data set. This paper describes the theory and implementation of this technique. Keywords: Computer Graphics, Scientific Visualization, 3D Texture Mapping, Direct Volume Rendering. 1 Overview Rendering speed has always been a major problem in ...
Volume Rendering using the Fourier ProjectionSlice Theorem
 Also Stanford University
, 1992
"... The Fourier projectionslice theorem states that the inverse transform of a slice extracted from the frequency domain representation of a volume yields a projection of the volume in a direction perpendicular to the slice. This theorem allows the generation of attenuationonly renderings of volume da ..."
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Cited by 48 (1 self)
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The Fourier projectionslice theorem states that the inverse transform of a slice extracted from the frequency domain representation of a volume yields a projection of the volume in a direction perpendicular to the slice. This theorem allows the generation of attenuationonly renderings of volume data in O (N 2 log N) time for a volume of size N 3 . In this paper, we show how more realistic renderings can be generated using a class of shading models whose terms are Fourier projections. Models are derived for rendering depth cueing by linear attenuation of variable energy emitters and for rendering directional shading by Lambertian reflection with hemispherical illumination. While the resulting images do not exhibit the occlusion that is characteristic of conventional volume rendering, they provide sufficient depth and shape cues to give a strong illusion that occlusion exists. Keywords: Volume rendering, Fourier projections, Shading models, Scientific visualization, Medical imaging...