Path: utzoo!attcan!uunet!ncrlnk!ncr-sd!hp-sdd!hplabs!ucbvax!ucsfcgl!pixar!loren
From: loren@pixar.UUCP (Loren Carpenter)
Newsgroups: comp.graphics
Subject: Re: anti-aliasing
Message-ID: <2795@pixar.UUCP>
Date: 11 Dec 88 09:03:38 GMT
References: <8812011358.AA19900@cartier.dgp.toronto.edu>
Reply-To: loren@pixar.UUCP (Loren Carpenter)
Organization: Pixar -- Marin County, California
Lines: 27

In article <8812011358.AA19900@cartier.dgp.toronto.edu> andreww@dgp.toronto.edu (Andrew Chung How Woo) writes:
	>
	>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

Rob Cook did this too.  He didn't call it "stratified sampling", though.
The idea is suggested by the solutions to the "8 queens problem".  You want
N sample points, no 2 of which are in the same column, and no 2 of which
are in the same row.  Then you jitter on top of that....

p.s.  You better not use the same pattern for each pixel...


			Loren Carpenter
			...!{ucbvax,sun}!pixar!loren