Generating soft shadows with a depth buffer algorithm

An algorithm is developed that combines an existing shadowing method with a popular visible surface rendering technique, called a depth buffer, to generate soft shadows resulting from light sources of finite extent.

Abstract

A pragmatic approach is taken to develop an algorithm that combines an existing shadowing method with a popular visible surface rendering technique, called a depth buffer, to generate soft shadows resulting from light sources of finite extent. The method extends F. Crow's shadow volume algorithm (1977) to produce multiple shadows overlapped to yield the characteristic soft edges of a shadow penumbra.