Quote - Depth map shadows are maps generated by the renderer.  They have size.  If an object fall within the size and shape generated by the algorithm, it's hit by the shadow map.  If the object doesn't fall within it, it's not covered by the shadow map.

This is a very simplistic explanation of a long and complex discussion I had back in the early P5 days with a friend who had a good deal more CG experience than I did.

 

Thanks.