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From: loren@pixar.UUCP (Loren Carpenter)
Newsgroups: rec.arts.startrek,comp.graphics
Subject: Re: Star Trek II graphics: "The Genesis Effect"
Keywords: star trek graphics genesis
Message-ID: <2534@pixar.UUCP>
Date: 10 Oct 88 01:02:28 GMT
Article-I.D.: pixar.2534
References: <277@pte.UUCP> <523@epicb.UUCP> <12672@oberon.USC.EDU>
Reply-To: loren@pixar.UUCP (Loren Carpenter)
Organization: Pixar -- Marin County, California
Lines: 52

This message is in need of some commentary...

 In article <12672@oberon.USC.EDU> ahoffman@skat.usc.edu (Alan M. Hoffman) writes:
 >An interesting sidebar to the "Genesis Effect" article is that all of those
 >funky "particle" sequences--the random "flames" and the wave effect--were
 >generated using fractical math.

The particle system effects (volcanoes & flames) didn't use any fractal math
at all.  They were, however, stochastically modelled (deterministically
repeatable random processes).  The fractal code was used on the mountains
and the cooling/molten surface after the flame passed by.

 >Fractals, as you know, are the hot new computer technique that "randomly"
 >produces realistic-looking mountains, vegetation, coastlines, and
 >other real-world pictures.

The "Genesis Demo" was computed in the Winter of 1981-1982.  The fractal
programs were an anti-aliased version of those I used in 1979 to make
"Vol Libre".

 >The reason each frame takes so long is that EVERY POINT in the array need
 >to be calculated in relation to surrounding points, and then a ray traced
 >back to the "observer" which determines whether it can be seen, what color
 >it is, and what kind of surface it has.  Last I heard, they were using a
 >version of the Cray 2 called an XMP, designed especially for graphics work,
 >to do the number crunching.  The final image is printed on a film recorder.

The frames took about 20-40 minutes each on a VAX 11/780 (with fpa).  There was
absolutely no "ray tracing" anywhere in there.  Rendering was done with the
A-buffer hidden surface method.  Frames were computed at 512x480 32-bits
(8 each rgb, plus 8 bits alpha matte).  Completed frames (stars + flames, etc)
were shot off a Barco monitor with a high quality 35mm movie camera.  The
director liked the "video" effect.  Now we use a film recorder.

We borrowed time on a couple of Cray XMP's to compute the character parts of
"The Adventures of Andre and Wally B.".  Neither we, nor Lucasfilm, have,
or ever had, a Cray of any flavor.  Not that we didn't want one. ;-)

 >Wish I could do that on my XT!
 
You can.  It might take a few hours per frame.  All you need is a C compiler
and a bunch of SIGGRAPH proceedings.  That's how we did it.


 >-----------------------------------  OOO  OOO   OOOOO   OOOOO  ---------------
 >    Alan M. Hoffman                 OOO  OOO  OOO     OOO   
 >    ARPA:  AHOFFMAN@skat.usc.edu   OOO  OOO     OOO  OOO  "The Rose Bowl 1989!
 >---------------------------------  OOOOOO    OOOOO    OOOOO  -----------------


			Loren Carpenter
			...{ucbvax,sun}!pixar!loren