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From: stevea@poincare.geom.umn.edu (stevea)
Newsgroups: sci.psychology,comp.graphics.visualization
Subject: Re: Real 3D PHOTOCOPY - black & white - no glasses...
Message-ID: <1991Apr29.225451.24699@cs.umn.edu>
Date: 29 Apr 91 22:54:51 GMT
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In article <4354.2816ba40@iccgcc.decnet.ab.com> fleischer@iccgcc.decnet.ab.com writes:
>I saw the most *amazing* "3D" black and white photocopy of an 
>advertisement by PENTICA.  It looked like a random patern of squiggles in
>a box with 2 large black dots above.  When you shift the focus of your eyes
>to make the 2 dots overlap, this flat XEROX'd picture turns 3D.  It's
>like you're looking through a window to a picture about 1 foot below the
>paper with letters and numbers at various heights above the picture.
>
>Does anyone know how this was done?  Is there PC software that will let 
>you build these and print them on a laser printer?  Is there a collection of
>these?  Who did the theory and development?  Does it require more resolution
>than exists on a VGA display?  IS there a dynamic/moving version?
>
>I requested more information from PENTICA, but I don't expect a very 
>detailed reply.

Sure, I've seen these around.  They're called "random dot stereograms", and
were invented by a psychologist named Julesz.  (I forgot his first name.)
He developed it 20 or 25 years ago, but the technique's mostly lain dormant
since then.  Until now.  There was an article in a recent issue of _Mathematica
Journal_, about how to create these.  (Using mathematica, I guess.)  I
don't know which issue.

Check out your local shopping districts too.  We got a huge poster for our
office from a shop that sells holograms and things.  The poster was produced
by Oliphant Research.  It's about 3'x 2', and full of geometric shapes
that seem to rise out of the paper.

-Steven Anderson	stevea@geom.umn.edu	Geometry Center of Minnesota