A few more drachmas regarding pseudos...

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

OK, before anyone says that I have something against "pseudo-stereos",
please let the record show that I have experimented with "pseudo
stereos" and have a couple of slides that I like.  "Pseudo-stereos"
are more of a spice than hyperstereos.  One must be careful of when
and how to use them, especially with ordinary stereophotographed scenes.

One of my pseudos circulated in the Alpha folio of the Stereoscopic 
Society.  Paul Wing killed this one in his comments.  He told us that 
this was not a good application of pseudo, and he pointed out that Ted 
Lambert was a well known creative stereo photographer that did a number 
of fine pseudo-stereos.

If you want to get a taste of Ted's work, check out PSA's subject sets 
(PSA members can borrow these from Henrietta Tinay).  There is one set 
by Ted Lambert ("This Is It" or something like that is the title).
One thing I learn from Ted's set is that the pseudo is viewed better 
if turned upside down.  

Any time you reverse a regular stereo, you have a conflict between
the reversed stereoscopic depth and the of the depth-related monocular 
cues.  In many cases this conflict results in confusion.  That's not
going to work.  But, there are cases where a new & interesting scene is 
born.  One needs to experiment a lot to get a feeling of what is going
to work and what is not going to work.

As expected, if the scene does not have strong monocular depth cues,
especially overlapping, like SEM stereo pairs or simple computer 
models, reversing the images can cause no conflict and this can be a 
problem if the correct visual interpretation is the goal.

The human face is a classic example of an object that is impossible
to experience with reverse depth.  Reversing a stereo of a human face
results in a flat image, not one where the nose goes back.

That's my two drachmas on the subject.

-- George Themelis

PS.  Just to identify another Greek stereo word:  "Ortho" means
"straight", "correct".  Could be the opposite of "pseudo"...


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