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A Visibility Field for Ray Tracing
 Constant Time Queries on Uniformly Distributed Points on a Hemisphere, Journal of Graphics Tools
, 2004
"... This paper presents a type of visibility data structure for accelerated ray tracing. The visibility field is constructed by choosing a regular point subdivision over a hemisphere to obtain a set of directions. Corresponding to each direction there is then a rectangular grid of parallel beams, with e ..."
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This paper presents a type of visibility data structure for accelerated ray tracing. The visibility field is constructed by choosing a regular point subdivision over a hemisphere to obtain a set of directions. Corresponding to each direction there is then a rectangular grid of parallel beams, with each beam referencing a set of identifiers corresponding to objects that intersect it. Objects lying along a beam are sorted using a 1D BSP along the beam direction. The beam corresponding to any ray can be looked up in small constant time and the set of objects corresponding to the beam can then be searched for intersection with the ray using an optimised traversal strategy. This approach trades off rendering speed for memory usage and preprocessing time. The data structure is also very suitable for hemisphere integration tasks due to its spherical nature and results for one such taskAmbient Occlusion are also presented. Results for several scenes with various rendering methods are presented and compare favourably with a well established approach, the singleray Coherent Ray Tracing approach of Wald and Slusallek et al. 1.
Fast ray tracing of scenes with unstructured motion
, 2004
"... Ray tracing dynamically changing scenes with unstructured motion for animated objects has long been a problem for raytraversal acceleration schemes. When polygons are transformed independently of one another, the cost of updating traditional ..."
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Ray tracing dynamically changing scenes with unstructured motion for animated objects has long been a problem for raytraversal acceleration schemes. When polygons are transformed independently of one another, the cost of updating traditional
A Nonparametric Guide for Radiance Sampling in Global Illumination
, 2007
"... Global illumination as described by the radiance and potential equations is essentially a sampling problem. This sampling has two elements: ‘where ’ to sample and ‘how’ to sample. In this paper we propose an alternative method to nonparametrically simplify the problem of ‘where ’ in the general cas ..."
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Global illumination as described by the radiance and potential equations is essentially a sampling problem. This sampling has two elements: ‘where ’ to sample and ‘how’ to sample. In this paper we propose an alternative method to nonparametrically simplify the problem of ‘where ’ in the general case. We present a solid angle based uniform sampling scheme with an efficient conservative cull of solid angles not affecting the transfer of radiance between two surfaces. This construction also provides a geometric area bounds within which a surface can receive energy from another along directions contained in the solid angle. The technique can be used to illuminate a scene from a general emitter, including incident light fields. The method has several applications and advantages, with results showing good sampling efficiency and speed.
Abstract Realtime Global Illumination in the CAVE
"... Global illumination in VR applications remains an elusive goal. While it potentially has a positive impact on presence, the significant realtime computation and integration complexities involved have been stumbling blocks. In this paper we present recent and ongoing work in the Virtual Light Field ..."
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Global illumination in VR applications remains an elusive goal. While it potentially has a positive impact on presence, the significant realtime computation and integration complexities involved have been stumbling blocks. In this paper we present recent and ongoing work in the Virtual Light Field paradigm for global illumination as a solution to this problem. We discuss its suitability for realtime VR applications and detail recent work in integrating it with the XVR system for realtime GPUbased rendering in a CAVE TM. This rendering method achieves realtime rendering of L(SD) ∗ E solutions in time independent of illumination complexity and largely independent of geometric complexity.
EUROGRAPHICS 2006 / D. W. Fellner and C. Hansen Short Papers Realtime Reflection using Ray Tracing with Geometry Field
"... A novel method for accurate reflections in real time is introduced using ray tracing in geometry fields, which combine light fields with geometry images. The geometry field of a surface is defined ray space, mapping a ray to its intersection point with the surface, represented as the uv coordinates ..."
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A novel method for accurate reflections in real time is introduced using ray tracing in geometry fields, which combine light fields with geometry images. The geometry field of a surface is defined ray space, mapping a ray to its intersection point with the surface, represented as the uv coordinates on the geometry image. It makes intersection tests much more efficient using lookups within a fragment shader, and allows conventional textures to be applied, such as normal maps, to enhance geometric subtleties. Our method can be generalized to also handle refraction and selfreflection. Experimental results demonstrate its capability for accurate reflection for complex scenes in realtime. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation I.3.7 [Computer Graphics]: ThreeDimensional Graphics and Realism Raytracing
Light Field Propagation and Rendering on the GPU
"... This paper describes an algorithm that provides fast propagation and realtime walkthrough for globally illuminated synthetic scenes. A type of light field data structure is used for propagating radiance outward from emitters through the scene, accounting for any kind of L(SD) ∗ light path. The li ..."
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This paper describes an algorithm that provides fast propagation and realtime walkthrough for globally illuminated synthetic scenes. A type of light field data structure is used for propagating radiance outward from emitters through the scene, accounting for any kind of L(SD) ∗ light path. The light field employed is constructed by choosing a regular point subdivision over a hemisphere, to give a set of directions, and then corresponding to each direction there is a rectangular grid of parallel rays. Each rectangular grid of rays is further subdivided into rectangular tiles, such that each tile references a sequence of 2D images containing outgoing radiances of surfaces intersected by the rays in that tile. We present a novel propagation algorithm running entirely on the Graphics Processing Unit (GPU). It is incremental in that it can resolve visibility along a set of parallel rays in O(n) time and can produce a light field for a moderately complex scene with complex illumination stored in millions of elements in minutes and for simpler scenes in seconds. It is approximate but gracefully converges to a correct solution as verified by comparing images with path traced counterparts. We show how to render globally lit images directly from the GPU data structure without CPU involvement at realtime frame rates and high resolutions. 1.