Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!ames!nap1!asdcds!staatsvr
From: staatsvr@asdcds.cds.wpafb.af.mil (Vern Staats; ASD/SCED;)
Newsgroups: comp.graphics
Subject: Re: How does radiosity work?
Keywords: radiosity
Message-ID: <273@nap1.cds.wpafb.af.mil>
Date: 25 Aug 89 16:21:00 GMT
References: <1540@ndmath.UUCP>
Sender: news@nap1.cds.wpafb.af.mil
Reply-To: staatsvr@asdcds.UUCP (Vern Staats)
Organization: US. Air Force, ASD, Wright-Patterson AFB
Lines: 38

In article <1540@ndmath.UUCP> milo@ndmath.UUCP (Greg Corson) writes:
>Would anyone care to offer a quick description of the radiosity process? 

  I don't know much about radiosity either, but I did attend a good talk 
given by Harry Baeverstad from Hewlett-Packard at the Ohio State University.  
The following are mostly direct qoutes from the viewcharts:

  The radiosity method correctly models the interaction of light between
reflecting surfaces if the surfaces are perfectly diffuse.  The light 
leaving a surface (its radiosity) consists of self-emitted light and
reflected or transmitted light.  The amount of light arriving at a 
surface requires a complete specification of the geometric relationships
among all reflecting and transmitting surfaces, as well as the light
leaving every surface.  Form factors are computed to determine the 
fraction of light leaving one surface which lands on another surface.  
The reflected light is equal to the light leaving every other surface 
multiplied by both the fraction of that light reaching its surface 
(form factor) and the reflectivity of the receiving surface.  The sum 
of the reflected light plus the light emitted from a surface is termed 
its radiosity.

Strengths:
1)  Based on fundamental energy equilibrium methods derived from thermal
    engineering.
2)  The most realistic images for diffuse environments - soft shadows and
    reflections.
3)  View independent; new viewing angles may be displayed interactively.

Weaknesses:
1)  Computationally expensive for initial solution.
2)  Not recommended for highly specular images (use ray-tracing).

. . . . and now you know everthing I know about radiosity.  Hope it helps.

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