P3D Re: 3-DVG

[Bruce Springsteen <bsspringsteen@xxxxxxxxx>]

Well, now that I have read the archives and all current postings on
this topic, I am full of information and still (not atypically)
confused, but happy.

Jim Crowell's suggestion of a number of known depth-illusion
principles working in concert is very plausible.  Ken's own
descriptions of what may lie behind 3-DVG seem not too different from
Jim's.  I still think the chromastereopsis aspect may be
over-emphasized, and that illusions provided gratis by the mind are at
work.  Like the illusion of cyclopic stereopsis the brain supplies in
some peoples' dreams!  I have tried Paul T's "litmus test" of closing
one eye during lucid dreams of stereo, but there is no "eye" to close
so the test is unperformable.  Sad to say.  I think the litmus test
may not be fair in DVG though, as it does not purport to be true
binocular stereopsis - just strongly similar in effect.

Still, I thought my claim that I can view the Dunkley effect without
pinholes or pinkies would be more of a provocation than it has been. 
I must just be lucky to be able to create a pinhole-like condition
with my unaided eyes and eyelids.  Makes dull movies fun!  I see that
color pictures are not necessary, which is a "relief" to me (as Bob
Weir would say: "Slight pun" - see also "Moderate Pun" and "Extreme
Pun").  I was concerned that I was doing an unauthorized trick by
seeing depth in flat black & white shots.  I will cancel the
appointments to have my eyes and head examined, and just enjoy the
pretty pictures.

Comments about varied individual sensitivity to depth illusions,
partly by nature and partly by training, seem true in my experience. 
I have become greatly sensitized to depth cues that a few years ago
would not have been noticeable to me.  I still enjoy "discontinuous"
depth, but now seem to prefer - and perceive - more subtle graduation
in scenes.  By the way, I also consider stereopsis in 3D photography
to be an "illusion".  There is no actual 3D scene there, just a pair
of projections following rules of perspective and parallax, which
"trick" the brain into imagining a real scene.  So describing DVG as
an illusion seems obvious to me and does not diminish its
respectability in any way.  Just don't say "delusion", "confusion" or
"collusion" - them's fightin' words! ;-);-)

I encourage people to learn this "trick".  Whatever the cause, it is
enjoyable and thought-provoking.   

Bruce "My auction strategy is:  Don't give away your auction
strategy!" Springsteen








 
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