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170
FAST VOLUME RENDERING USING A SHEARWARP FACTORIZATION OF THE VIEWING TRANSFORMATION
, 1995
"... Volume rendering is a technique for visualizing 3D arrays of sampled data. It has applications in areas such as medical imaging and scientific visualization, but its use has been limited by its high computational expense. Early implementations of volume rendering used bruteforce techniques that req ..."
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Cited by 446 (2 self)
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Volume rendering is a technique for visualizing 3D arrays of sampled data. It has applications in areas such as medical imaging and scientific visualization, but its use has been limited by its high computational expense. Early implementations of volume rendering used bruteforce techniques that require on the order of 100 seconds to render typical data sets on a workstation. Algorithms with optimizations that exploit coherence in the data have reduced rendering times to the range of ten seconds but are still not fast enough for interactive visualization applications. In this thesis we present a family of volume rendering algorithms that reduces rendering times to one second. First we present a scanlineorder volume rendering algorithm that exploits coherence in both the volume data and the image. We show that scanlineorder algorithms are fundamentally more efficient than commonlyused ray casting algorithms because the latter must perform analytic geometry calculations (e.g. intersecting rays with axisaligned boxes). The new scanlineorder algorithm simply streams through the volume and the image in storage order. We describe variants of the algorithm for both parallel and perspective projections and
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 ..."
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Cited by 247 (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.
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 88 (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.
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...
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 68 (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...
Volumetric reconstruction and interactive rendering of trees from photographs
 ACM Transactions on Graphics (SIGGRAPH Conference Proceedings
, 2004
"... Figure 1: Our method captures and renders existing trees from photographs, by estimating opacity in a volume, then generating and displaying viewdependent textures attached to cells of the volume. (a) One of the original photographs of an oak. (b) The α mask used for the opacity estimation. Two cro ..."
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Cited by 58 (1 self)
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Figure 1: Our method captures and renders existing trees from photographs, by estimating opacity in a volume, then generating and displaying viewdependent textures attached to cells of the volume. (a) One of the original photographs of an oak. (b) The α mask used for the opacity estimation. Two cross slices of the resulting opacity are shown in (c). A synthetic image of the original view, using our viewdependent rendering, is shown in (d). Textures are attached to billboards in cells of the volume and are generated based on estimated opacity. Reconstructing and rendering trees is a challenging problem due to the geometric complexity involved, and the inherent difficulties of capture. In this paper we propose a volumetric approach to capture and render trees with relatively sparse foliage. Photographs of such trees typically have single pixels containing the blended projection of numerous leaves/branches and background. We show how we estimate opacity values on a recursive grid, based on alphamattes extracted from a small number of calibrated photographs of a tree. This data structure is then used to render billboards attached to the centers of the grid cells. Each billboard is assigned a set of viewdependent textures corresponding to each input view. These textures are generated by approximating coverage masks based on opacity and depth from the camera. Rendering is performed using a viewdependent texturing algorithm. The resulting volumetric tree structure has low polygon count, permitting interactive rendering of realistic 3D trees. We illustrate the implementation of our system on several different real trees, and show that we can insert the resulting model in virtual scenes.
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 53 (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 ...
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 53 (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...
Simulating Arthroscopic Knee Surgery using Volumetric Object Representations, RealTime Volume Rendering and Haptic Feedback
, 1997
"... A system for simulating arthroscopic knee surgery that is based on volumetric object models derived from 3D Magnetic Resonance Imaging is presented. Feedback is provided to the user via realtime volume rendering and force feedback for haptic exploration. The system is the result of a unique collabo ..."
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Cited by 48 (1 self)
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A system for simulating arthroscopic knee surgery that is based on volumetric object models derived from 3D Magnetic Resonance Imaging is presented. Feedback is provided to the user via realtime volume rendering and force feedback for haptic exploration. The system is the result of a unique collaboration between an industrial research laboratory, two major universities, and a leading research hospital. In this paper, components of the system are detailed and the current state of the integrated system is presented. Issues related to future research and plans for expanding the current system are discussed. Introduction Computerbased surgical simulation has many applications in education and training, surgical planning, and intraoperative assistance. Given the low availability and high cost of cadaver and animal specimens, surgical simulation can be used in medical education and training to reduce costs, to provide experience with a greater variety of pathologies and complications, and...
ZSWEEP: An Efficient and Exact Projection Algorithm for Unstructured Volume Rendering
, 2000
"... We present a simple new algorithm that performs fast and memoryefficient cell projection for (exact) rendering of unstructured datasets. The main idea of the "ZSweep" algorithm is very simple; it is based on sweeping the data with a plane parallel to the viewing plane, in order of increasing z, pro ..."
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Cited by 47 (14 self)
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We present a simple new algorithm that performs fast and memoryefficient cell projection for (exact) rendering of unstructured datasets. The main idea of the "ZSweep" algorithm is very simple; it is based on sweeping the data with a plane parallel to the viewing plane, in order of increasing z, projecting the faces of cells that are incident to vertices as they are encountered by the sweep plane. The efficiency arises from the fact that the algorithm exploits the implicit (approximate) global ordering that the zordering of the vertices induces on the cells that are incident on them. The algorithm projects cells by projecting each of their faces, with special care taken to avoid double projection of internal faces and to assure correctness in the projection order. The contribution for each pixel is computed in stages, during the sweep, using a short list of ordered face intersections, which is known to be correct and complete at the instant that each stage of the computation is comple...