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From: jon@oddhack.UUCP
Newsgroups: comp.graphics
Subject: Re: AmigaWorld Ray-Tracing Article
Message-ID: <2443@cit-vax.Caltech.Edu>
Date: Thu, 23-Apr-87 16:06:21 EST
Article-I.D.: cit-vax.2443
Posted: Thu Apr 23 16:06:21 1987
Date-Received: Sat, 25-Apr-87 06:37:45 EST
References: <1514@sphinx.uchicago.edu> <804@elrond.CalComp.COM>
Sender: news@cit-vax.Caltech.Edu
Reply-To: jon@oddhack.Caltech.EDU (Jon Leech)
Organization: California Institute of Technology
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In article <804@elrond.CalComp.COM> amamaral@elrond.CalComp.COM (Alan Amaral) writes:
>Again, slow is relative.  I believe it was Jim Kajiya, one of the
>foremost authorities on computer graphics and raytracing, at the last
>SIGGRAPH conference that said "Ray tracing is not slow, computers 
>are slow. Some day someone will build a $99.00 zillion mflop machine
>and EVERYONE will be doing ray tracing in real time."

	The reason this doesn't work is that the images we want to
render are continually growing more complex in the quest for realism.
One of the students here raytraced a picture containing 4e11 polygons
last fall (of course, there were several levels of instantiation - 
we can't fit that much in memory yet). Some sort of hierarchical 
enclosure scheme is required to render scenes of even moderate
complexity.

	Another way of expressing this is what I have come to call
``Jim Blinn's law of Constant Image Generation Time'': Given an
individual and a computer, the amount of time the individual is
willing to spend rendering an image is roughly constant. Thus, as
computers get faster, images LOOK BETTER, but take just as long to
make. For people who need to make large quantities of material, the
time constant is ~5 min/frame. For people who want realism, it's more
like 8-12 hours/frame. 

    -- Jon Leech (jon@csvax.caltech.edu || ...seismo!cit-vax!jon)
    Caltech Computer Science Graphics Group
    __@/