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From: jon@oddhack.Caltech.Edu (Jon Leech)
Newsgroups: net.graphics
Subject: Re: Y positive up or down? / Left or right-handed?
Message-ID: <1102@cit-vax.Caltech.Edu>
Date: Fri, 31-Oct-86 12:27:28 EST
Article-I.D.: cit-vax.1102
Posted: Fri Oct 31 12:27:28 1986
Date-Received: Sat, 1-Nov-86 04:30:24 EST
References: <1338@batcomputer.TN.CORNELL.EDU>
Sender: news@cit-vax.Caltech.Edu
Reply-To: jon@csvax.caltech.edu (Jon Leech)
Organization: California Institute of Technology
Lines: 22
Keywords: Handedness, Physics, Religion

In article <1338@batcomputer.TN.CORNELL.EDU> garry%cadif-oak@cu-arpa.cs.cornell.edu writes:
>A related question: in 3-D, do people like left-handed coordinates,
>right-handed, or programmer-choosable ?  
>...
>I heard a rumor once that most solid geometry books are right-handed...
>
>garry wiegand   (garry%cadif-oak@cu-arpa.cs.cornell.edu)

	This is another of the innumerable religious debates in computer
graphics. An amusing story along these lines: Jim Blinn has done a great
deal of computer generated material for the PBS series ``The Mechanical
Universe''. His SIGGRAPH film 2 years ago contained portions of this
material with his own narration. At one point, while talking about
tops or some such, he said 'of course, vectors obey the right-hand rule',
which received applause from the knowedgable members of the audience.
Jim's rendering software uses LHS internally, leading to more work than would
otherwise be neeeded. The point is that if you're doing modeling based
on real physics, you work in RHS - and it makes life that much easier
if your other software talks the same coordinate system. 
    -- Jon Leech (jon@csvax.caltech.edu || ...seismo!cit-vax!jon)
    Caltech Computer Science Graphics Group
    __@/