Re: Re: The problem with Pulfrich

[P3D Jim Crowell <crowell@xxxxxxxxxxxxxxxxx>]

At 8:01 PM 8/22/96, P3D Larry Berlin wrote:

>> Bob Wier writes:
>>I'd be curious to know if anyone has ever researched whether the effect
>>with Pulfrich gives you "real" stereo vision, or something that just
>>looks like it?
>
>I'm extremely new to the Pulfrich effect but my limited experience shows
>that there are varying effects depending on relative motion. The greater the
>degree of motion, the greater the disparity and apparent relative depth. The
>effect is true stereo *WHEN it is present* because there is a difference
>between the left and right views that the mind is interpreting.
>

That's my understanding as well; other than the delay to one
eye, the percept is a consequence of the same set of processes
that are responsible for regular stereo...

>
>It does tend to have the "cardboard cutout" sensation because the whole of
>an object is usually moving at the same rate. It would be very difficult to
>create roundness of objects with the Pulfrich effect, unless the objects
>themselves were in some precise relative motion too.

No, unless the camera is panning (in which case you'll get no
depth anywhere) or the object is rotating so that the same point
on its surface is always pointed at the camera, the Pulfrich
effect should give rise to relative disparities between parts of
the object at different depths.  They may be too small to
detect, however.

-Jim C.


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Jim Crowell
School of Optometry
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