From: schmidtg@iccgcc.decnet.ab.com
Subject: SCI: SIRDS
Date: 9 Mar 92 12:52:24 EST
Message-ID: <1992Mar9.125225.7489@iccgcc.decnet.ab.com>



Hello,

I've recently been introduced to sirds (single image random dot stereograms)
and my initial reaction was WOW!.  These are computer generated dot patterns
which have a steroscopic effect when properly focused on.  Several of them
appear in the April issue of GAMES magazine.  They are intriguing since they
are contained in a single image and do not require any additional devices
(3D glasses etc..) to view.  It takes a bit of practice do develop the proper
focusing technique, however once attained it becomes easy (much like riding a
bicycle).  Apparently, these images are produced by first generating a back-
ground of random black and white dots.  Dimensional images are then created
by shifting the dots in an amount proportional to the desired depth illusion
to be created.  I was able to create a simple sird by duplicating the random
dot patterns within a square against a random background.

Now a question, does anyone have any information on this technique or on
sirds in general?  I would be interested in knowing the algorithm used to
generate these as I would like to create some more complex ones.


-- Greg

+===========================================================================+
| Greg Schmidt ---> schmidtg@iccgcc.decnet.ab.com                           |
+---------------------------------------------------------------------------+
|"People with nothing to hide have nothing to fear from O.B.I.T"            |
|	-- Peter Lomax                                                      |
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| Disclaimer: None of my statements can absolutely be proven to be correct. |
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