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From: shirley@iuvax.cs.indiana.edu (peter shirley)
Newsgroups: comp.graphics
Subject: Re: Trying to get soft shadows
Keywords: ray tracing shadows soft areas lights
Message-ID: <1991Mar20.080218.27371@news.cs.indiana.edu>
Date: 20 Mar 91 13:01:26 GMT
References: <1991Mar20.104448.3681@nntp-server.caltech.edu>
Organization: Computer Science, Indiana University
Lines: 15

Just like pixel sampling, light source sampling works better is the
"random" points are replaced by "quasi-random" points.  Quasi-random
points can be generated by making sure no two points are too close, or
by hand generating them for storage in lookup tables.

See the ray tracing book under jittering or Poisson disk sampling for
further details.

pete
shirley@cs.indiana.edu


PS- I think you'll have better luck choosing points on the projected area
of the light source.  Choosing from within the sphere would be correct if
the light originated throughout the sphere.