An efficient shadow algorithm for area light sources using BSP trees

The paper presents a fast algorithm for computing shadow volumes of area light sources and performing shadow classification. The algorithm improves Chin and Feiner's method (N. Chin and S. Feiner, 1992) in the way that it does not subdivide an area light source before the processing of scene polygons. Instead, a light source is only subdivided when needed and is merged immediately when the need vanishes. Much redundant work is saved by avoiding the unnecessary subdivisions. Compared with Chin and Feiner's method, experiments show that the new method can run faster without loss of accuracy.