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From: lance@motcsd.csd.mot.com (lance.norskog)
Newsgroups: comp.graphics
Subject: Re: renderman
Message-ID: <2528@motcsd.csd.mot.com>
Date: 11 Jan 91 00:57:22 GMT
References: <1992@m1.cs.man.ac.uk> <2490@motcsd.csd.mot.com> <1991Jan7.143225.10246@pyro.ei.dupont.com> <240@coplex.UUCP>
Organization: Motorola CSD, Cupertino CA
Lines: 28

dean@coplex.UUCP (Dean Brooks) writes:

  [ My deathless prose deleted ]

>Excuse my ignorance of the subject, but is Renderman a commercial only
>library?  
>...  
>There are several raytrace libraries
>available, but few live up to the photorealism that Renderman has
>been proven to produce.

Yes, it's a product of Pixar.  Pixar is a spin-off of the Lucasfilm
empire, and is part-owned by Steve Jobs.  Renderman started as 
Lucasfilm's inhouse movie graphics production system.

Renderman is not a ray-tracer.  It uses the Reyes (render everything you
ever saw) algorithm.  This is described in various SIGGRAPHs from the
mid-80's.  I haven't studied it, but apparently the algorithm is to 
break all elements of the scene into "micro-polygons" smaller than
a pixel.  Then, apply radiosity, ray-tracing, and arcane tricks
to the resulting humongous collection of tiny graphics chunks.

Since everything is smaller than a pixel, simple algorithms and 
approximations suffice where complex algorithms don't work very well
on larger objects.  Also, the resulting dataset partitions well over
parallel processors.

Lance