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