[ATM] viewing in stereo - a bit off topic, but interesting anyway

[koehler at securecomputing.com (Stephen C. Koehler)]

Guy,

I can relate an interesting and unexpected (to me) effect of this sort of
stereoscopic modification.

A number of years ago, I fooled around with taking stereo slides using a
normal (not a stereo) camera.  It's easy to do.  Take one picture,
remembering exactly where you were aiming.  Move to the left or right by
some distance.  Take a second picture aiming at the same spot.  The
resulting slides can be viewed in pairs in an inexpensive stereo slide
viewer.

I took a couple of roles of stereo shots on a trip to the Grand Canyon.
I took many shots with a separation of about 1 foot.  Then, I thought I
could enhance the stereo effect by moving larger distances between the 
shots.  I tried a few feet, 10 feet, and even something like 50 feet for
very distant shots.  The results were very strange.  The wider the 
separation, the smaller the items in the photo looked.  For example, 6'
pinyon pines in the middle distance looked like 3" miniatures in a diorama.
When looking at these pictures, you cannot get your brain to make those
trees look like 6' trees.

So, yes, it did enchance the stero effect, but it also changed the sense 
of scale in the photos.  Apparently we very strongly use the stereo effect
in deciding how big things are.

Now that I think about it, it would be very easy for people to fool around 
with this using a digital camera.  The shots can be put side-by-side on a
computer screen, and the images merged without a stereo viewer.  When I get
a chance, I will try to put together a demonstration of the effect I 
described above.
-- 
Steve Koehler
koehler@securecomputing.com