Newsgroups: comp.graphics
Path: utzoo!utgpu!jarvis.csri.toronto.edu!dgp.toronto.edu!andreww
From: andreww@dgp.toronto.edu (Andrew Chung How Woo)
Subject: anti-aliasing
Message-ID: <8812011358.AA19900@cartier.dgp.toronto.edu>
Organization: University of Toronto, CSRI
Date: Thu, 1 Dec 88 08:58:49 EST

With all these discussions about anti-aliasing for ray tracing, I thought I 
would get into the fun also.

As suggested by many people, adaptive sampling is a good way to start
dealing with anti-aliasing (suggested by Whitted).  For another quick
hack ontop of adaptive sampling, you can add jitter (suggested by Cook).
The jitter factor can be controlled by the recursive depth of the
adaptive sampling.  This combination tends to achieve decent quality.

Another method which nobody has mentioned is "stratified sampling".  This
is also a rather simple method.  Basically, the pixel is divided into a 
N-size grid.  You have a random number generator to sample a ray at (x,y) of 
the grid.  Then shoot another ray, making sure that the row x and column y 
are discarded from further sampling, etc.  Repeat this for N rays.  Note,
however, no sharing of point sampling information is available here.

Andrew Woo