Discusses the hierarchical geometric models for visible surface algorithms. Effect of extension of traditional structure information on systems for producing pictures by computer; Relationship between visiblesurface...
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Discusses the hierarchical geometric models for visible surface algorithms. Effect of extension of traditional structure information on systems for producing pictures by computer; Relationship between visiblesurface algorithm computation time and visible complexity of the scene.
The visiblesurface problem is to determine those subpolygons of a 3-D scence of arbitrary simple planar polygons which are visible from a given viewpoint. The algorithm which is presented here, and which is designed ...
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The visiblesurface problem is to determine those subpolygons of a 3-D scence of arbitrary simple planar polygons which are visible from a given viewpoint. The algorithm which is presented here, and which is designed for complex scenes solves this problem by an implicit partitioning w.r.t. a raster of cells. The estimation of complexity leads to propositions on the favorable choice of the grid, and to the characterization of classes of scenes, which are relevant for practical applications, and for which the algorithm shows a linear time and space behavior.
The classical Z-buffer visibility algorithm samples a scene at regularly spaced points on an image plane. Previously, we introduced an extension of this algorithm called the irregular Z-buffer that permits sampling of...
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The classical Z-buffer visibility algorithm samples a scene at regularly spaced points on an image plane. Previously, we introduced an extension of this algorithm called the irregular Z-buffer that permits sampling of the scene from arbitrary points on the image plane. These sample points are stored in a two-dimensional spatial data structure. Here we present a set of architectural enhancements to the classical Z-buffer acceleration hardware which supports efficient execution of the irregular Z-buffer. These enhancements enable efficient parallel construction and query of certain irregular data structures, including the grid of linked lists used by our algorithm. The enhancements include flexible atomic read-modify-write units located near the memory controller, an internal routing network between these units and the fragment processors, and a MIMD fragment processor design. We simulate the performance of this new architecture and demonstrate that it can be used to render high-quality shadows in geometrically complex scenes at interactive frame rates. We also discuss other uses of the irregular Z-buffer algorithm and the implications of our architectural changes in the design of chip-multiprocessors.
We present a new method for computing visibility from a polygonal region in the plane considering a set of line segments as occluders. The proposed method provides a comprehensive description of visibility from the gi...
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We present a new method for computing visibility from a polygonal region in the plane considering a set of line segments as occluders. The proposed method provides a comprehensive description of visibility from the given region. We represent sets of occluded rays using a hierarchical partitioning of dual space (line space). The line space partitioning is maintained by a BSP tree that provides efficient operations on the sets of lines. The implementation shows that the method is suitable for computing potentially visible sets in large scenes with various visibility characteristics. (C) 2003 Elsevier Ltd. All rights reserved.
Focuses on the improved illumination model for shaded display system. Storage of information in a tree of 'rays'; Creation of the tree for the display pixel by visiblesurface algorithm; Inclusion of anti-alia...
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Focuses on the improved illumination model for shaded display system. Storage of information in a tree of 'rays'; Creation of the tree for the display pixel by visiblesurface algorithm; Inclusion of anti-aliasing as an integral part of visibility calculations.
To accurately render a scene, global illumination information that affects the intensity of each pixel of the image must be known at the time the intensity is calculated. In a simplified form, this information is stor...
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ISBN:
(纸本)9780897910040
To accurately render a scene, global illumination information that affects the intensity of each pixel of the image must be known at the time the intensity is calculated. In a simplified form, this information is stored in a tree of “rays” extending from the viewer to the first surface encountered and from there to other surfaces and to the light sources. The visiblesurface algorithm creates this tree for each pixel of the display and passes it to the shader. The shader then traverses the tree to determine the intensity of the light received by the viewer. Consideration of all of these factors allows the shader to accurately simulate true reflection, shadows, and refraction as well as the effects simulated by conventional shaders. Anti-aliasing is included as an integral part of the visibility calculations. surfaces displayed include curved as well as polygonal surfaces.
A visiblesurface algorithm with integrated analytic spatial and temporal anti-aliasing is presented. This algorithm models moving polygons as four dimensional (X,Y,Z,T) image space polyhedra, where time (T) is treate...
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ISBN:
(纸本)9780897911665
A visiblesurface algorithm with integrated analytic spatial and temporal anti-aliasing is presented. This algorithm models moving polygons as four dimensional (X,Y,Z,T) image space polyhedra, where time (T) is treated as an additional spatial dimension. The linearity of these primitives allows simplification of the analytic algorithms. The algorithm is exact for non-intersecting primitives, and exact for the class of intersecting primitives generated by translation and scaling of 3-d (X,Y,Z) polygons in image space. This algorithm is an extension of Catmull's analytic visiblesurface algorithm for independent pixel processing, based on the outline of integrated spatial and temporal anti-aliasing given by Korien and Badler. An analytic solution requires that the visiblesurface calculations produce a continuous representation of visible primitives in the time and space dimensions. visiblesurface algorithm, graphical primitives, and filtering algorithm, (by Feibush, Levoy and Cook) are extended to include continuous representation of the additional dimension of time. A performance analysis of the algorithm contrasted with a non-temporally anti-aliased version is given.
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