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From: aburke@ogicse.cse.ogi.edu (Andrew Burke)
Newsgroups: comp.graphics
Subject: good radiosity question
Message-ID: <20917@ogicse.ogi.edu>
Date: 3 May 91 00:42:27 GMT
Sender: aburke@ogicse.ogi.edu
Organization: Oregon Graduate Institute (formerly OGC), Beaverton, OR
Lines: 28


a few days ago wuly@vax5.cit.cornell.edu queried the net:
>> Howdy.
>> 	I have written a combination radiosity/raytracing rendering system
>> (whew!) and I'm somewhat confused on one point: I have a scene of 5 walls,
>> 10x10, with a light 3x3 pointing at one of the walls.  Now with 90% diffuse
>> surfaces, the relative energy out of the wall *behind* the light (i.e. light
>> left the lightsource, hit the wall in front, and was re-radiated to the back
>> wall, and re-radiated again) is about 1/1000 the energy leaving the light.
>> This seems wrong. ...

I have basically the same problem. I've read all the papers, scratched a 
bald spot on my head, but still am a bit puzzled. My code also just doesn't
seem quite correct. My solution has been to either increase the intensity
of the source light, or to make the surface area of the light source larger.
Clearly, though, if someone at Cornell is having problems (how close can you
get to Donald Greenberg & Co.?), many of us would benefit if someone posted
a standard radiosity scene which we all could use as a reference. This wouldn't
mean the poster would make our jobs any easier (everyone is getting pretty
paranoid about giving away "secrets" these days), it would just allow us
to confirm we're on the right track.

In any case, I also would be interested in any light anyone can shed on
this subject. 

andrew burke
aburke@cse.ogi.edu
"Reboot the system"