[photo-3d] Re: The wobble effect

[Jim Crowell <crowell@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

> Gabriel Jacob wrote:
> I do it all the time! :-) Often when I get a left and right stereo pair on the
> computer
> and view them sequentially (using a image program specializing in viewing
> and cataloging) I notice the sudden perspective shift of the image and the
> seemingly 3-D depth. I believe this depth is simply motion parallax, which
> is a close second to stereoscopic depth perception. Note, motion parallax
> is not a stereoscopic depth cue.

Actually, for anything other than sitting still & close distances (a few
meters) it's better than stereo.  Part of the reason that motion parallax
gives you a weaker depth sensation on the screen is that it's usually
created by the motion of your head through the world.  If you could yoke the
wobble precisely to sideways motion of your head (or yoke head motion to the
wobble, if you can do it accurately enough :-) ), you should get a more
stereo-like sensation.

> Joshua Rubin wrote:
> Try this:  Go to the large snowflake "wobble" image at
> http://www.lpsi.barc.usda.gov/emusnow/stereo/1.htm and view the image while
> covering one eye.  To my eye, it's not only 3-D, it's actually slightly more
> 3-D than if I look at it with both eyes.
> 

When you have both eyes open, the stereo is actually conflicting with the
motion parallax, telling you that it's a flat picture.  Closing one eye
removes the conflict.

It's a cool idea, I'll have to put it as an option into my viewer program...

-Jim C.

-------------------------------------
Jim Crowell, Ph.D.
Dept. of Psychology
Cognitive/Experimental Group
216 Lazenby Hall
Ohio State University
Columbus, OH 43210
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