Re: 3-D phenomenon

[P3D Allan Woods <allanwx@xxxxxxxxxx>]

>
>But the reason we 'discard' it in a Realist slide is because our vision is
>dynamic!
>
>When I sit here and focus on my finger and blur the background, "reality"
>doesn't go out-of-focus (imagine if it did, and anybody could blur out
>reality on you at any time!).  All of reality is "in-focus" all of the
>time; it is our *vision system* that is selectively focusing, and yes,
>that does give us a depth cue.  But we do exactly the same thing when we
>view a Realist slide *if* it contains both near (in front of the window)
>and far subjects (behind the window).  I recently took such a shot, as
>an experiment.  I framed a tree through the hole in a concrete playground
>sculpture/climbing thing that looks roughly like a 4 foot tall slice of
>brown Swiss cheese.  Both the sculpture (which is in front of the window)
>and the tree (about 100ft away) are in sharp focus.  But when you shift
>your viewpoint to the sculpture, the tree goes blurry and double, and
>vice-versa.  It's rough on the eyes, but it demonstrates to me that the
>Realist format isn't 'discarding' anything.
>
>... (stuff deleted)
>	-Greg
>
>
Like I said before, I am NOT trying to say anything is BETTER - just
trying to understand where things come from.

Another important "autonomic" clue our brains use is the degree of
divergence or convergence our eyes use to shift near/distant viewing.

It happens auto-magically; we don't pay much attention to it, but it
goes into the mix - (remember, anatomically the eyes are part of the brain).

So, we're looking at a projected stereo Realist slide where everything
is as sharp as we like it and it all sort of looks right.  We can let
out eyes wander over the image and no matter where we look, it appears
to be "in focus" - BUT we are doing a lot of compensating because
something - LOTS of things aren't quite right.  For one thing our
eyes are always converged on THE SURFACE OF THE SCREEN where the virtual
image is.  That doesn't happen when you just look at stuff.

And if you move your head (carrier pilots maneouvre) perspective
and parallax don't work either.


Also, as you mentioned, in "real life," the objects in your peripheral
field of view are out of focus, but as soon as you turn your attention
to them, they are in focus.

So, convergence of eyeballs, out of focus periphery are more things
which are part of seeing "normally."  In fact peripheral vision has
major visual clues we don't think we notice.  Remember Cinerama? Or
that round "See America" thing they used to have at Disneyland?  Or
the 2-D OmniDome, MaxiDome things?

So, two sharp images properly mounted look "pretty good."  They fool
us quickly and relatively convincingly - but after viewing this
simulated 3-D for a while, we need to stop.  Too much "compensating"
for what just doesn't match reality going on.  We get a headache,
our eyes get tired because it isn't a 100% "true" representation
of what we see.

I'm not advocating SL-3D for pictures of the SouthWest - but neither
can you get a Realist close enough to see the spherical structure
of Volvox - and, if we're doing micro-surgery on my body, I'd prefer
a two-eyed doctor to a one-eyed doctor, wouldn't you?

allanwx@xxxxxxxxxx



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