Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!noao!amethyst!spock!chris
From: chris@spock (Chris Ott)
Newsgroups: comp.graphics
Subject: Re: ShowScan
Message-ID: <888@amethyst.ma.arizona.edu>
Date: 31 Jan 89 23:22:59 GMT
Sender: news@amethyst.ma.arizona.edu
Reply-To: chris@spock.ame.arizona.edu (Chris Ott)
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Organization: Computational Fluid Mechanics Lab, U of A, Tucson
Lines: 42


> cs161agc@sdcc10.ucsd.EDU (John Schultz) writes:
> > chris@spock.ame.arizona.edu (Chris Ott) writes:
> >     Actually, I've heard that someone (George Lucas maybe?) has
> >experimented with a setup where showing 60 frames/sec allows the audience
> >to see in 3D _without_ glasses. Supposedly, they just alternate between
> >eyes, i.e. show a frame for the left eye for 1/60th of a second then a
> >frame for the right eye for another 1/60th of a second, and so on, so the
> >effective frame rate is actually 1/30th of a second. Still, 3D without
> >glasses sounds pretty nice.
>
>   How can this work? Both eyes will see both images.  ShowScan
> itself has an almost 3D quality, but alternating left/right images
> at 60hz will produce a noticeable "double image" if the left/right
> eyes are not masked from the opposite right/left display frames.
> They must be doing something else other than alternating stereo
> pairs.  I generate stereo 3D on the Amiga by the same technique as
> described above, but we use an LCD shutter the mask off the
> appropriate images...

     It's some sort of mind trick. You know, like mixing red and green
to get yellow. You think you're seeing yellow, but you're really seeing
red and green mixed. Your eye can't tell the difference.

     What I'm talking about works because the brain can only process
information at 1/60th of a second or something like that. Your visual
processing center automatically figures which frame goes with which
eye and you can see in 3D. However, I've heard that it doesn't work
for everyone, only about 95% of the people who have seen it.

>  John Schultz

--Chris

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 Chris Ott
 Computational Fluid Mechanics Lab        Infatuation is blind, not love. A
 University of Arizona                      person in love can see the other's
                                            faults, but loves them anyway.
 Internet: chris@spock.ame.arizona.edu
 UUCP: {allegra,cmcl2,hao!noao}!arizona!amethyst!spock!chris
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