Use of Variance Shadow Map to Accelerate Ray Tracing

Abstract

Ray tracing has been widely employed to compute the global illumination in computer graphics. Due to numerous ray-primitive intersection testing operations, ray tracing is very time-consuming. In this paper, we proposed a variance shadow map based algorithm to perform the shadow testing in ray tracing. This algorithm does not need to carry out the inefficient intersection testing operations between a shadow ray and geometric primitives. It computes the visibility between a point and a light source by querying the variance shadow map and hence can greatly enhance the speed of the shadow testing. The details of implementing our algorithm in the framework of ray tracing were presented. The performance comparison between our algorithm and the original shadow testing in ray tracing was also drawn theoretically. Our algorithm provides a new alternative to accelerate ray tracing.