An algorithm is presented for display of Constructive Solid Geometry (CSG) models, in which Boolean evaluation of a model is done during image generation only for the visible parts of the model. The algorithm is based...
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A visible surface 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 visible surface 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 visible surface 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 visible surface calculations produce a continuous representation of visible primitives in the time and space dimensions. Visible surface 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.
A general purpose Cellular Array Processor(CAP) with distributed frame buffers for fast parallel subimage generation has been developed. CAP consists of many processor elements called cells. A cell has video memory fo...
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ISBN:
(纸本)9780897911665
A general purpose Cellular Array Processor(CAP) with distributed frame buffers for fast parallel subimage generation has been developed. CAP consists of many processor elements called cells. A cell has video memory for subimage storage, a window controller to map each subimage to an area on the monitor screen, and communication devices, in addition to ordinary microcomputer components such as MPU, RAM, and ROM. Image data in a cell is directly displayed via the video bus. The mapping pattern and the position on the screen of subimages can be changed dynamically. Various hidden surface algorithms can be implemented in CAP using mapping patterns appropriate for the *** goal is an efficient interactive visual solid modeler. We adopted a general CSG hidden surface algorithm that enables display of both Boundary representation and Constructive Solid Geometry. A technique for hidden surface removal of general CSG models, requiring less memory space for large models in many cases, has been proposed. This technique subdivides the model into submodels by dividing the CSG tree at union nodes. Imagse of each submodel are generated by a CSG or a z-buffer algorithm. If a submodel is just a primitive, it is processed by the z-buffer algorithm, otherwise by the CSG algorithm. Hidden surface removal between submodels is done by comparing the z values for each pixel which are saved in the z-buffer.
Invisibility coherence is a new technique developed to decrease the time necessary to render shaded images by existing scan-line hidden surface algorithms. Invisibility coherence is a technique for removing portions o...
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ISBN:
(纸本)9780897911382
Invisibility coherence is a new technique developed to decrease the time necessary to render shaded images by existing scan-line hidden surface algorithms. Invisibility coherence is a technique for removing portions of a scene that are not likely to be visible. If a large portion of the scene is invisible, as is often the case in three-dimensional computer graphics, the processing time eliminated may be substantial. Invisibility coherence takes advantage of the observation that a minimal amount of processing needs to be done on objects (polygons, patches, or surfaces) that will be hidden by other objects closer to the viewer. This fact can be used to increase the efficiency of current scan-line algorithms, including both polygon-based and parametrically curved surface-based *** coherence was implemented and tested with the polygon hidden surface algorithm for constructive solid geometry developed by Peter Atherton [1]. The use of invisibility coherence substantially increases the efficiency of this scan-line algorithm. Invisibility coherence should work as well or even better with other scan-line hidden surface algorithms, such as the Lane-Carpenter, Whitted, and Blinn algorithms for parametrically curved surfaces [2]., or the Watkins, Romney, and Bouknight algorithms for polygons [3, 4, 5].
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