Invisibility coherence for faster scan-line hidden surface algorithms

Abstract

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 algorithms. Invisibility 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].