P3D Re: "impossible" images in stereo

[Peter Davis <pd@xxxxxxxxxxxxx>]

I suspect it is due to the ambiguity of the image.  In the third pair, the 
"inside" balls are supposed to correspond, and the outside pair are 
supposed to correspond.  However, I don't think the brain has any way to 
determine this where both pairs are present, so it takes the simplest 
interpretation ... the left goes with the left, and the right goes with the 
right.

Anyway, that's my guess.

-pd

At 09:54 PM 3/7/00, you wrote:
>John Roberts writes:
> >The 2D "impossible images" take advantages of the fact that there's only
> >one view, in order to fool the human perceptual system in an interesting
> >way. So - can anyone think of stereo (2-view) images that take advantage
> >of the fact that there are only two views, to fool the human perceptual
> >system in interesting ways?
>
>I'm not sure if this fits the bill, but it does fool the senses in an
>interesting way. I don't take credit for it, which I found in some
>publication (forget exactly where) sometime ago.
>
>
>In the first ascii stereo pair (use fixed pitch fonts to see this
>correctly), you'll see the ball (o) behind the window, if your
>parallel viewing and above the window if cross-eyed viewing.
>                   _____________________ _____________________
>                  |                     |                     |
>                  |                     |                     |
>                  |         o           |           o         |
>                  |                     |                     |
>                  |_____________________|_____________________|
>
>In the next ascii stereo pair, you'll see the ball above the window,
>if your parallel-viewing and behind if cross-eyed viewing.
>                   _____________________ _____________________
>
>                  |                     |                     |
>                  |                     |                     |
>                  |           o         |         o           |
>                  |                     |                     |
>                  |_____________________|_____________________|
>
>Now here is where it gets interesting. If you put the both balls in
>the same image, you would expect one to be behind and the other to
>be above the window. Problem is they would BOTH now be AT the
>window, regardless if you freeview parallel or cross-eyed!
>                   _____________________ _____________________
>
>                  |                     |                     |
>                  |                     |                     |
>                  |         o o         |         o o         |
>                  |                     |                     |
>                  |_____________________|_____________________|
>
>I'll leave it up to you all, to figure out why!
>
>Gabriel

--------
                              Peter Davis
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