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From: raney@yertle.Colorado.EDU (Scott Raney)
Subject: Re: Real 3D on plain black n' white photocopy. No special glasses....
Message-ID: <1991Apr26.160423.20871@colorado.edu>
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Date: Fri, 26 Apr 1991 16:04:23 GMT
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Fusing random dot stereograms without glasses is not all that difficult.
Hold the figures 12"-18" away from your eyes, cross your eyes till you
see three figures (instead of just the two on the page), relax your focus
keeping the size of the middle image the same size as the two originals.
Eventually (it may take a few seconds, or even a few minutes if you're
new at it) a 3-D image will appear.  The image is actually fairly stable
across eye movements and page movements if they are of short distance and
if there is sufficient delay between movements. David Marr's book Vision
has examples as do the PDP (Rumelhart and McClelland) and most vision
texts, if you don't happen to have one handy.

Have fun, and I guarantee your eyes won't stay that way (despite what
your mother may have told you).

Scott

-- 
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Scott Raney                            No other person or organization
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