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76
Efficient ray tracing of volume data
 ACM Transactions on Graphics
, 1990
"... Volume rendering is a technique for visualizing sampled scalar or vector fields of three spatial dimensions without fitting geometric primitives to the data. A subset of these techniques generates images by computing 2D projections of a colored semitransparent volume, where the color and opacity at ..."
Abstract

Cited by 325 (4 self)
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Volume rendering is a technique for visualizing sampled scalar or vector fields of three spatial dimensions without fitting geometric primitives to the data. A subset of these techniques generates images by computing 2D projections of a colored semitransparent volume, where the color and opacity at each point are derived from the data using local operators. Since all voxels participate in the generation of each image, rendering time grows linearly with the size of the dataset. This paper presents a fronttoback imageorder volumerendering algorithm and discusses two techniques for improving its performance. The first technique employs a pyramid of binary volumes to encode spatial coherence present in the data, and the second technique uses an opacity threshold to adaptively terminate ray tracing. Although the actual time saved depends on the data, speedups of an order of magnitude have been observed for datasets of useful size and complexity. Examples from two applications are given: medical imaging and molecular graphics.
A Clustering Algorithm for Radiosity in Complex Environments
, 1994
"... 1 Introduction Recent trends in realistic image synthesis have been towards a separation of the rendering process into two or more stages[10, 2, 9]. One of these stages solves for the global energy equilibrium throughoutthe environment. This process can be very expensive and its complexity grows ra ..."
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Cited by 130 (5 self)
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1 Introduction Recent trends in realistic image synthesis have been towards a separation of the rendering process into two or more stages[10, 2, 9]. One of these stages solves for the global energy equilibrium throughoutthe environment. This process can be very expensive and its complexity grows rapidly with the number of objects in the environment.These computational demands generally limit the level of detail of environments that can be simulated. Furthermore, a solution to thisproblem must be computed before anything useful can be displayed.
Multilevel ray tracing algorithm
 ACM Trans. on Graphics
, 2005
"... We propose new approaches to ray tracing that greatly reduce the required number of operations while strictly preserving the geometrical correctness of the solution. A hierarchical “beam” structure serves as a proxy for a collection of rays. It is tested against a kdtree representing the overall sc ..."
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Cited by 124 (2 self)
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We propose new approaches to ray tracing that greatly reduce the required number of operations while strictly preserving the geometrical correctness of the solution. A hierarchical “beam” structure serves as a proxy for a collection of rays. It is tested against a kdtree representing the overall scene in order to discard from consideration the subset of the kdtree (and hence the scene) that is guaranteed not to intersect with any possible ray inside the beam. This allows for all the rays inside the beam to start traversing the tree from some node deep inside thus eliminating unnecessary operations. The original beam can be further subdivided, and we can either continue looking for new optimal entry points for the subbeams, or we can decompose the beam into individual rays. This is a hierarchical process that can be adapted to the geometrical complexity of a particular view direction allowing for efficient geometric antialiasing. By amortizing the cost of partially traversing the tree for all the rays in a beam, up to an order of magnitude performance improvement can be achieved enabling interactivity for complex scenes on ordinary desktop machines.
Interactive Global Illumination using Fast Ray Tracing
, 2002
"... Rasterization hardware provides interactive frame rates for rendering dynamic scenes, but lacks the ability of ray tracing required for efficient global illumination simulation. Existing ray tracing based methods yield high quality renderings but are far too slow for interactive use. We present a ..."
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Cited by 110 (19 self)
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Rasterization hardware provides interactive frame rates for rendering dynamic scenes, but lacks the ability of ray tracing required for efficient global illumination simulation. Existing ray tracing based methods yield high quality renderings but are far too slow for interactive use. We present a new parallel global illumination algorithm that perfectly scales, has minimal preprocessing and communication overhead, applies highly efficient sampling techniques based on randomized quasiMonte Carlo integration, and benefits from a fast parallel ray tracing implementation by shooting coherent groups of rays. Thus a performance is achieved that allows for applying arbitrary changes to the scene, while simulating global illumination including shadows from area light sources, indirect illumination, specular effects, and caustics at interactive frame rates. Ceasing interaction rapidly provides high quality renderings.
The Visibility Skeleton: A Powerful And Efficient MultiPurpose Global Visibility Tool
, 1997
"... Many problems in computer graphics and computer vision require accurate global visibility information. Previous approaches have typically been complicated to implement and numerically unstable, and often too expensive in storage or computation. The Visibility Skeleton is a new powerful utility which ..."
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Cited by 89 (6 self)
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Many problems in computer graphics and computer vision require accurate global visibility information. Previous approaches have typically been complicated to implement and numerically unstable, and often too expensive in storage or computation. The Visibility Skeleton is a new powerful utility which can efficiently and accurately answer visibility queries for the entire scene. The Visibility Skeleton is a multipurpose tool, which can solve numerous different problems. A simple construction algorithm is presented which only requires the use of well known computer graphics algorithmic components such as raycasting and line/plane intersections. We provide an exhaustive catalogue of visual events which completely encode all possible visibility changes of a polygonal scene into a graph structure. The nodes of the graph are extremal stabbing lines, and the arcs are critical line swaths. Our implementation demonstrates the construction of the Visibility Skeleton for scenes of over a thousan...
Clustering for Glossy Global Illumination
 ACM TRANSACTIONS ON GRAPHICS
, 1997
"... We present a new clustering algorithm for global illumination in complex environments. The new algorithm extends previous work on clustering for radiosity to allow for nondiffuse (glossy) reflectors. We represent clusters as points with directional distributions of outgoing and incoming radiance and ..."
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Cited by 62 (4 self)
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We present a new clustering algorithm for global illumination in complex environments. The new algorithm extends previous work on clustering for radiosity to allow for nondiffuse (glossy) reflectors. We represent clusters as points with directional distributions of outgoing and incoming radiance and importance, and we derive an error bound for transfers between these clusters. The algorithm groups input surfaces into a hierarchy of clusters, and then permits clusters to interact only if the error bound is below an acceptable tolerance. We show that the algorithm is asymptotically more efficient than previous clustering algorithms even when restricted to ideally diffuse environments. Finally, we demonstrate the performance of our method on two complex glossy environments.
Uniformly Sampled Light Fields
, 1998
"... Imagebased or light field rendering has received much recent attention as an alternative to traditional geometric methods for modeling and rendering complex objects. A light field represents the radiance flowing through all the points in a scene in all possible directions. We explore two new techni ..."
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Cited by 42 (2 self)
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Imagebased or light field rendering has received much recent attention as an alternative to traditional geometric methods for modeling and rendering complex objects. A light field represents the radiance flowing through all the points in a scene in all possible directions. We explore two new techniques for efficiently acquiring, storing, and reconstructing light fields in a (nearly) uniform fashion. Both techniques sample the light field by sampling the set of lines that intersect a sphere tightly fit around a given object. Our first approach relies on uniformly subdividing the sphere and representing this subdivision in a compact data structure which allows efficient mapping of image pixels or rays to sphere points and then to subdivision elements. We sample a light field by joining pairs of subdivision elements and store the resulting samples in a multiresolution, highly compressed fashion that allows efficient rendering. Our second method allows a uniform sampling of all five dime...
Modeling plants with environmentsensitive automata
 In Proceedings of Ausgraph’88
, 1988
"... Abstract We present a new approach for modeling plants which allows for adaptation to geometrical and material properties of a simulated environment. The form of a plant is derived from the paths of one or more automata which begin as seeds and progressively explore the environment. The automata sen ..."
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Cited by 29 (0 self)
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Abstract We present a new approach for modeling plants which allows for adaptation to geometrical and material properties of a simulated environment. The form of a plant is derived from the paths of one or more automata which begin as seeds and progressively explore the environment. The automata sense their surroundings by casting rays and using intersection information to influence subsequent patterns of growth. In this way the power of wellknown ray tracing techniques is applied to a problem of geometric modeling. By seeking locations which satisfy various environmental criteria such as proximity to surfaces and availability of light, the automata extend the repertoire of simulated plant growth to include emulation of phenomena such as clinging vines and heliotropism. This approach to database amplification can be used in conjunction with previous methods such as particle systems and graftals. Introduction Many methods have been devised for modeling botanical forms for computer graphics. Lindenmayer [10] introduced rewriting grammars to model simple forms of biological growth, and later
Filtering, Clustering and Hierarchy Construction: a New Solution for RayTracing Complex Scenes
 COMPUTER GRAPHICS FORUM
, 1995
"... Data structures that handle very complex scenes (hundreds of thousands of objects) have in the past either been laboriously built by hand, or have required the determination of unintuitive parameter values by the user. It is often the case that an incorrect choice of these parameters can result in g ..."
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Cited by 29 (4 self)
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Data structures that handle very complex scenes (hundreds of thousands of objects) have in the past either been laboriously built by hand, or have required the determination of unintuitive parameter values by the user. It is often the case that an incorrect choice of these parameters can result in greedy memory requirements or severely degraded performance. As a remedy to this problem we propose a new data structure which is fully automatic since it does not require the user to determine any input parameters. The structure is built by first filtering the input objects by size, subsequently applying a clustering step to objects of the same size and finally building a hierarchy of uniform grids (HUG). We then show that this data structure can be efficiently constructed. The implementation of the HUG shows that the new structure is stable since it's memory requirements grow linearly with the size of the scene, and that it presents a satisfactory compromise between memory usage and computa...
Applying Space Subdivision Techniques to Volume Rendering
 IEEE Visualization
, 1990
"... We present a new raytracing algorithm for volume rendering which is designed to work efficiently when the data of interest is distributed sparsely through the volume. A simple preprocessing step identifies the voxels representing features of interest. Frequently this set of voxels, arbitrarily dist ..."
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Cited by 28 (2 self)
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We present a new raytracing algorithm for volume rendering which is designed to work efficiently when the data of interest is distributed sparsely through the volume. A simple preprocessing step identifies the voxels representing features of interest. Frequently this set of voxels, arbitrarily distributed in three dimensional space, is a small fraction of the original voxel grid. A mediancut space partitioning scheme, combined with bounding volumes to prune void spaces in the resulting search structure, is used to store the voxels of interest in a kd tree. The tree is then efficiently raytraced to render the voxel data. The kd tree is view independent and can be used for animation sequences involving changes in positions of the viewer or positions of lights. We have applied this search structure to render voxel data from MRI, CAT Scan and electron density distributions. 1 Introduction An increasingly important application of computer graphics technology is in providing visualiza...