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From: carroll@s.cs.uiuc.edu
Newsgroups: comp.graphics
Subject: Re: 3-D perceptual abilities
Message-ID: <207400002@s.cs.uiuc.edu>
Date: 4 Mar 89 18:37:00 GMT
Lines: 17
Nf-ID: #R:<cXsBOzy00XoZM0ml5i@andrew.cmu.e:-35:s.cs.uiuc.edu:207400002:000:965
Nf-From: s.cs.uiuc.edu!carroll    Mar  4 12:37:00 1989


RE: 3-D from repeating 2-D patterns

I first noticed this staring up at the roof of a dodge van, with a regular
patterns of holes in it. I've since learned how to do it on demand, even
on a keyboard (so it looks like the keys have ``stretched'' up toward me).
Look straight down at the G H keys, and let your eyes go unfocused and
somewhat crossed. Try to get the image of the G on the right to overlap
the H on the left, and then (slowly) try to focus in on this 'GH' key.
Don't try to see what letter is on it clearly - this forces your brain to
make a choice, and destroys the perception. The same technique works (for me)
on any repeating pattern, by letting the images slide onto one another.
P.S. I haven't experienced asteriopsis or the distance effect, though.

Alan M. Carroll          "And then you say,
carroll@s.cs.uiuc.edu     We have the Moon, so now the Stars..."  - YES
CS Grad / U of Ill @ Urbana    ...{ucbvax,pur-ee,convex}!s.cs.uiuc.edu!carroll