Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!apple!portal!fernwood!shograf!jack
From: jack@shograf.COM (Jack Ritter)
Newsgroups: comp.graphics
Subject: Re: Ray Tracing Optimization Idea
Summary: seems to be novel
Keywords: Exploit coherence
Message-ID: <560@shograf.COM>
Date: 22 Mar 91 17:13:31 GMT
References: <1991Mar21.183340.19319@dartvax.dartmouth.edu>
Organization: SHOgraphics
Lines: 28

In article <1991Mar21.183340.19319@dartvax.dartmouth.edu>, npw@eleazar.dartmouth.edu (Nicholas Wilt) writes:
> efficient.  Cache the last object intersected; intersect with it
> first and if hit, determine whether it is still the nearest object as
> follows:
> 	1. Fire a ray from the intersection back at the eye
> 	2. If no object is intersected, the cached object is still nearest

I think this may be similar to other schemes
of "depth coherence". But this idea has a
twist: tracing from the last visible object to
the eye and stopping when anything is hit
is just like tracing shadow rays back to
lite sources, and therefore all the tricks
we've learned in shadow testing could
be used with this "last obj in view" idea.
(Then again, maybe I read that in some
article).

-------------------------
"The traffic lights, they turn blue tomorrow"
     Jimmie Hendrix

Jack Ritter
SHO Graphics
1890 N Shoreline Blvd.
Mountain View, CA 94043
email: jack@shograf.com
Tele:  (415) 903-3867