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From: metzger@heathcliff.columbia.edu.UUCP
Newsgroups: net.graphics
Subject: Re: any multi-processor ray tracing?
Message-ID: <2742@columbia.UUCP>
Date: Mon, 14-Jul-86 13:31:47 EDT
Article-I.D.: columbia.2742
Posted: Mon Jul 14 13:31:47 1986
Date-Received: Mon, 14-Jul-86 22:34:42 EDT
References: <249@vaxb.calgary.UUCP>
Sender: nobody@columbia.UUCP
Reply-To: metzger@heathcliff.UUCP (Perry Metzger)
Organization: Columbia University CS Department, Project DADO
Lines: 40
Keywords: ray tracing, multi-processing, mesh

In article <249@vaxb.calgary.UUCP> pearce@calgary.UUCP (Andrew Pearce) writes:
>Does anyone out there know of any research into multi-processor ray tracing?

>I know of the LINKS hardware in Japan, Micheal Ullner's thesis, Dippe and
>Swensen's SIGGRAPH paper, Apollo's "Long ray's journey into light" (but have
>not seen anything written about this), Fujimoto's "ARTS" in CG&A, and, of
>course, what John Cleary and I are doing here. But I've not heard of
>anyone else.

I am working on a ray tracer to run on the DADO computer we are building here
at Columbia. Dado 2 (the current iteration) is basically 1023 processors
in a complete binary tree. The machine has a great deal of flexibility in
how you can manage the processors, although communication is restricted to
Parent-child communication (as one would expect in a tree machine.)

>Although any information would be greatly appreciated, I'm not interested
>so much in vectorization or pipelining the algorithm as in arrays of
>processors running identical code with differing data spaces.

>For example, while simply dividing the screen into sub-sections and having
>each sub-section assigned to a distinct processor with global scene space
>knowledge is multi-processing, the processors in such a case do not require
>inter-processor communication durring the ray tracing procedure.

We am trying to exploit the machine's flexibility to explore several strategies
for ray tracing. The one currently being worked on uses a one object/processor
strategy, and the machine is used as a dedicated intersection finder.

But other techniques also look promising. One idea floating about is to use
the machine partitioning to effect space partitioning. Since DADO is fairly
medium grained a lot of exploring seems to be possible.

Well, anyone else out there involved in anything in the way of multi processor
ray tracing? It looks like a promising area of research, and a discussion here
can only benifit everyone.

Perry Metzger

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