Improved Computational Methods for Ray Tracing

This paper describes algorithmic procedures that have been implemented to reduce the computational expense of producing ray-traced images. The selection of bounding volumes is examined to reduce the computational cost of the ray-intersection test. The use of object coherence, which relies on a hierarchical description of the environment, is then presented. Finally, since the building of the rayintersection trees is such a large portion of the computation, a method using image coherence is described. This visible-surface preprocessing method, which is dependent upon the creation of an "item buffer," takes advantage of a priori image information. Examples that indicate the efficiency of these techniques for a variety of representative environments are presented.