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From: c184-bp@cube.Berkeley.edu (Rick Braumoeller)
Newsgroups: comp.graphics
Subject: Combining radiosity and ray-tracing
Message-ID: <C184-BP.91Jun8222718@cube.Berkeley.edu>
Date: 9 Jun 91 05:27:18 GMT
Sender: news@pasteur.Berkeley.EDU
Distribution: comp.graphics
Organization: CS Department
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I am interested in combining a radiosity project that I've recently
written with a friend's ray tracer.  I'm stumped on a couple of
questions -- hopefully, one of you out there with the time can help me out.

1)  It seems to me that ray tracing is very happy to have light
sources seperate from the objects in the scene, whereas radiosity
insists that they are objects in the scene.  Personally, I wouldn't
mind treating them differently from the rest of the objects in the
scene.  This would, however, throw a wrench into the radiosity part of
the program.  Any hints?

2)  Ray tracing is also very happy to use arbitrary objects, as long
as you can write functions to do intersection, normals, etc. with that
object.  But radiosity -- how about a sphere?  Do you tesselate it to
break it into patch/subpatches, and then render from each tesselated
face to give out the sphere's energy?  Since radiosity needs to have
patches, I don't see a "good" way to model something like a sphere
using that method.

3)  As far as I can tell, adaptive subdivision during the radiosity
pass is for the benefit of the viewer only -- it does not affect how
MUCH energy moves between surfaces, only where on the surface it goes.
Since I will be combining these two methods, I will, essentially, have
a view-DEpendant rendering.  Should I take advantage of the fact that
I know where the eyepoint is in the radiosity pass, and use that so
that I only subdivide things that I will wind up seeing in the ray
tracing pass(es)?

Thanks in advance for any tips, pointers, or casual observations --
email is appreciated, but not required.

- Rick Braumoeller
University of California, Berkeley