Interesting... I can't for the life of me figure out how it works, though, the whole "imperfect shadow map" thing. I think I get the implementation of the shadow map itself, especially in creating the broad soft shadows indicative of area lights (but I'm assuming without the usual performance hit), but I don't see how it's affecting the indirect lighting. Unless... hm.. *gears grinding*... the location of the main light, and the diffuse illumination of the mesh, is used to color and position another "invisible" light source that's casting no light, but rather an imperfect "positive" shadow from the opposite direction.. generating illumination instead of shadows. Fascinating. I should try to implement that in my CGI work sometime.. would save a HUGE amount of rendering time, since I usually have to resort to full-bore radiosity to calculate indirect lighting.
