Re: Diarama effect?

[P3D Jim Crowell <crowell@xxxxxxxxxxxxxxxxx>]

At 9:52 AM 7/9/96, P3D Peter Davis wrote:

>I was looking at some Realist slides yesterday, and noticed that my
>outdoor shots all appear to have a flat backdrop.  The effect is
>somewhat like a diarama display ... the foreground objects are
>dimensional and solid, but the distant background almost looks
>painted.  I realize that apparent depth is going to diminish with
>distance, but this seems more pronounced than I would expect.  Has
>anyone else experienced this?  Is it a known phenomenon?

Sure 'nuff.  Two hypothetical reasons: (1) your perception of
depth & shape for distant objects is normally based on motion
parallax (caused by your own motion), which is absent in the
stereoview; (2) your brain is interpreting the background as
being closer than it was in the original scene & weighting the
fact that there's no disparity between right & left images
accordingly.  At a great distance, any object will give rise to
(approximately) zero disparity; at a nearer distance, only a
really flat object will.

-Jim C.


------------------------------------------------
Jim Crowell
School of Optometry
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University of California
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