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Algorithms for computing diffuse reflection paths in polygons

by Subir Kumar Ghosh, Partha Pratim Goswami, Anil Maheshwari, Subhas Chandra Nandy, Sudebkumar Prasant Pal, Swami Sarvattomananda
"... Let s be a point source of light inside a polygon P of n vertices. A polygonal path from s to some point t inside P is called a diffuse reflection path if the turning points of the path lie on polygonal edges of P. We present three different algorithms for computing diffuse reflection paths from s t ..."
Abstract - Cited by 4 (1 self) - Add to MetaCart
Let s be a point source of light inside a polygon P of n vertices. A polygonal path from s to some point t inside P is called a diffuse reflection path if the turning points of the path lie on polygonal edges of P. We present three different algorithms for computing diffuse reflection paths from

An Algorithm for Computing Constrained Reflection Paths in Simple Polygons1

by Arijit Bishnu, Subir Kumar Ghosh, Partha Pratim Goswami, Sudebkumar Prasant Pal, Swami Sarvattomananda
"... Let s be a point source of light inside a simple polygon P of n vertices. A path from s to some point t inside P is called a diffuse reflection path if the turning points of the path lie in the interiors of the boundary edges of P. A diffuse reflection path is said to be optimal if it has the minimu ..."
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. The constrained diffuse reflection path computed by our algorithm has at most c times the number of turns in the optimal diffuse reflection path, where 2 ≤ c ≤ 4. 1

Beam tracing polygonal objects

by Paul S Heckbert , Pat Hanrahan - In Computer Graphics (Proceedings of ACM SIGGRAPH , 1984
"... Abstract Ray tracing has produced some of the most realistic computer generated pictures to date. They contain surface texturing, local shading, shadows, reflections and refractions. The major disadvantage of ray tracing results from its point-sampling approach. Because calculation proceeds ab init ..."
Abstract - Cited by 214 (1 self) - Add to MetaCart
the reflections are linear transformations, and refractions are often approximately so. The recursive beam tracer begins by sweeping the projection plane through the scene. Beam-surface intersections are computed using two-dimensional polygonal set operations and an occlusion algorithm similar to the Weiler

Inverse Global Illumination: Recovering Reflectance Models of Real Scenes from Photographs

by Yizhou Yu, Paul Debevec, Jitendra Malik, Tim Hawkins , 1999
"... In this paper we present a method for recovering the reflectance properties of all surfaces in a real scene from a sparse set of photographs, taking into account both direct and indirect illumination. The result is a lighting-independent model of the scene's geometry and reflectance properties, ..."
Abstract - Cited by 246 (12 self) - Add to MetaCart
estimates of both the radiance and irradiance of each patch from the photographic data. The algorithm computes the expected location of specular highlights, and then analyzes the highlight areas in the images by running a novel iterative optimization procedure to recover the diffuse and specular reflectance

The radiance lighting simulation and rendering system

by Gregory J. Ward - In Proceedings of SIGGRAPH 94, ACM SIGGRAPH / ACM , 1994
"... This paper describes a physically-based rendering system tailored to the demands of lighting design and architecture. The simulation uses a light-backwards ray-tracing method with extensions to efficiently solve the rendering equation under most conditions. This includes specular, diffuse and direct ..."
Abstract - Cited by 298 (8 self) - Add to MetaCart
. Some of the more interesting techniques are outlined, with references to more detailed descriptions elsewhere. Finally, examples are given of successful applications of this free software by others. CR Categories: I.3.3 [Computer Graphics]: Picture/image generation- Display algorithms; I.3.7 [Computer

An Optimal Algorithm for Euclidean Shortest Paths in the Plane

by John Hershberger, Subhash Suri - SIAM J. Comput , 1997
"... We propose an optimal-time algorithm for a classical problem in plane computational geometry: computing a shortest path between two points in the presence of polygonal obstacles. Our algorithm runs in worst-case time O(n log n) and requires O(n log n) space, where n is the total number of vertice ..."
Abstract - Cited by 114 (2 self) - Add to MetaCart
We propose an optimal-time algorithm for a classical problem in plane computational geometry: computing a shortest path between two points in the presence of polygonal obstacles. Our algorithm runs in worst-case time O(n log n) and requires O(n log n) space, where n is the total number

Short and smooth polygonal paths

by James Abello, Emden Gansner - Proc. 3rd Latin American Symp. Theoretical Informatics (LATIN '98), LNCS , 1998
"... Abstract. Automatic graph drawers need to compute paths among vertices of a simple polygon which besides remaining in the interior need to exhibit certain aesthetic properties. Some of these require the incorporation of some information about the polygonal shape without being too far from the actual ..."
Abstract - Cited by 4 (1 self) - Add to MetaCart
the actual shortest path. We present an algorithm to compute a locally convex region that “contains ” the shortest Euclidean path among two vertices of a simple polygon. The region has a boundary shape that “follows ” the shortest path shape. A cubic Bezier spline in the region interior provides a “short

An Efficient Algorithm for Euclidean Shortest Paths Among Polygonal Obstacles in the Plane

by Sanjiv Kapoor, Sachindra N. Maheshwari, Joseph S. B. Mitchell , 1988
"... We give an algorithm to compute a (Euclidean) shortest path in a polygon with h holes and a total of n vertices. The algorithm uses O(n) space and requires O(n + h² log n) time. ..."
Abstract - Cited by 45 (1 self) - Add to MetaCart
We give an algorithm to compute a (Euclidean) shortest path in a polygon with h holes and a total of n vertices. The algorithm uses O(n) space and requires O(n + h² log n) time.

A hierarchical illumination algorithm for surfaces with glossy reflection

by Pat Hanrahan - In SIGGRAPH 93 , 1993
"... We develop a radiance formulation for discrete three point transport, and a new measure and description of reflectance:area reflectance. This formulation and associated reflectance allow an estimate of error in the computation of radiance across triples of surface elements, and lead directly to a hi ..."
Abstract - Cited by 61 (3 self) - Add to MetaCart
hierarchical refinement algorithm for global illumination. We have implemented and analyzed this algorithm over surfaces exhibiting glossy specular and diffuse reflection. Theoretical growth in light transport computation is shown to beO(n+k 3) for sufficient refinement, where n is the number of elements

Diffuse Reflection Radius in a Simple Polygon?

by Eli Fox-epstein, Csaba D. Tóth, Andrew Winslow
"... Abstract. Light reflecting diffusely off of a surface leaves in all direc-tions. It is shown that every simple polygon with n vertices can be il-luminated from a single point light source s after at most b(n − 2)/4c diffuse reflections, and this bound is the best possible. A point s with this proper ..."
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Abstract. Light reflecting diffusely off of a surface leaves in all direc-tions. It is shown that every simple polygon with n vertices can be il-luminated from a single point light source s after at most b(n − 2)/4c diffuse reflections, and this bound is the best possible. A point
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