Re: One-Eyed Stereo and Visidep?

[P3D Andrew Woods <andrew@xxxxxxxxxxxxxxxxxxxxx>]

<SCHUB@xxxxxxxxxxxxxxxxxx> wrote:
>    The recent discussion of one-eyed stereo reminded me of a supposedly
> glasses-less 3-D TV system of a few years back called "Visidep", developed,
> as I recall, by a couple of professors at U. of South Carolina.

The two men in question were Edwin Jones and Andy McLaurin, of U. South
Carolina as you say.

> The descriptions of the thing seemed to indicate that all it did was rapidly
> alternate the left-eye and right-eye views on the screen; i.e., it was just
> like watching a field-sequential display without the shutter glasses!
> Since I've watched field-sequential displays without shutter glasses and
> never experienced any sense of 3-D, I've thought it couldn't possibly work.
> But this business of rocking a lenticular back and forth while looking at it
> with one eye sounds like it would be a similar effect, so I'm wondering if 
> some people DO experience the feeling of stereo in such situations.  Did 
> anyone on the list ever see "Visidep" demonstrated?  Am I correct in 
> surmising how it "worked"?  Did it alternate the fields more slowly than 
> typical shutter-glasses systems?

>From memory I believe that the switching between alternate fields was
done at the rate of between 4 and 10 Hz.  i.e. not very fast.
The system was shown on the US show "That's Incredible!" (cringe) in
probably about 1982.  I remember watching it as a kid and yes you definitely
do get a sense of depth in the image.  Not quite the same, however, as
seeing it in true stereo.  

This technique is basically invokes the depth cue of motion parallax.
When you move your head from side to side, things closer to you move
faster than things further away.  The brain can therefore infer depth from
the speed at which the objects move.

This motion parallax technique is also used in work by Christopher Mayhew 
(Vision III Imaging Inc.).  His work has focused on developing lenses for
production film and video cameras which provide a circular or eliptical
motion of the image to invoke the motion parallax cue.  His work
appeared in a paper a the recent Stereoscopic Displays and Applications
Conference "Parallax Scanning Using a Single Lens".  Some information
on the proceedings volume is available at my web site 
"http://info.curtin.edu.au/~iwoodsa/spie96"
and the abstract is available at the spie web site.

Andrew Woods.


------------------------------