Efficient image-based methods for rendering soft shadows.

Maneesh Agrawala Ravi Ramamoorthi Alan Heirich Laurent Moll Efficient image-based methods for rendering soft shadows. 375-384 2000 SIGGRAPH http://portal.acm.org/citation.cfm?id=344779.344954 db/conf/siggraph/siggraph2000.html#AgrawalaRHM00