P3D Re: The Stereo Window (was: More Lenticular Queries)

["Greg Wageman" <gjw@xxxxxxxxxx>]

From: abram klooswyk <abram.klooswyk@xxxxxx>


>I have said (elsewhere) that a stereo window is common to
>_all_ 3D images with visible borders.

We must then agree to disagree.  A "window" is something one sees
through.  If the border, edge or "window" is behind all the subject
matter, it is not a "window" because one does not "see through" it.

>Their visible physical or virtual borders necessarily are
>_anywhere_ on a specific place in space, as is the 3D scene
>they contain. Therefore the border has a defined perceptual
>position with respect to the 3D scene.


I agree with that.

>Image points of flat 2D pictures have X and Y coordinates,
>as have points of their border.
>Image points of 3D scenes additionally have Z coordinates,
>or, more simple said, lay at different distances from the
>spectator. Visible borders also have a Z-coordinate, they
>are at _some_ percepted distance from the viewing person.


Inarguably true.  To frame my assertion in your terms, if the Z
coordinates of the so-called "window" all lie at a greater distance than
the Z-coordinates of everything in the scene, it is not a "window" at
all.  There may still be a physical border, or edge, but it doesn't
constitute a window.

I notice that Tony did not respond to my query, does a 2D photograph
have a "stereo window"?

Everyone seems to be ducking that question!

>Remember that we also speak (with twin-view stereo) of a
>"stereo window at infinity", when there was no window set
>up in the camera or in mounting.
>So I'm not in favor of restricting the meaning of the
>concept of "stereo window", as Greg seems to want.


I think "window at infinity", while a commonly understood usage, is a
misnomer.  I see that it may be a battle already lost to try to resist
it, however.

>I don't quite understand what Greg means with "monocular
>frame" or "monocular border".
>Monocular is: seen with one eye only.

You are right in that it is a poor choice of terminology.  Perhaps
"single frame" is better, in contrast to the "double frame" of
stereoviews and slide pairs.

>Now there are 3D images _without_ visible borders.
>
>I my opinion these non-border examples are only special
>cases, or tricks, which don't mean that having a window
>isn't the general rule in 3D images.


Well, that's some progress.  We have reached a consensus that not all 3D
images have a window.

     -Greg W. (gjw@xxxxxxxxxx)



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