From: dstamp@watserv1.waterloo.edu (Dave Stampe-Psy+Eng)
Subject: Re: 1-eyed 3D
Date: Mon, 2 Dec 1991 18:46:30 GMT
Message-ID: <1991Dec2.184630.2854@watserv1.waterloo.edu>
Organization: University of Waterloo


ee91ajh@brunel.ac.uk (Adam J Holt) writes:

>Does anybody know anything about the (seemingly new) idea of 3D using a single
>filter over one eye.  It seems to be similar to the polaroid method used in
>the cinema but I realise that method couldn't be easily implemented on a
>conventional TV/monitor.  This system however has already been used on some
>Maybe somebody has seen the video(or similar).  If so please let me know if 
>the effect was good - maybe how it compares with the cinema polaroids.

The effect relies on the Purkinje effect: if one eye gets a darker image
of a scene than the other, the time delay imposed by the retinal sensors
becomes skewed between eyes and horizontal motion in the picture is
converted into "pseudo-depth".  Actually it has almost no correspondence
to real depth: your brain justs believes the 3D perspective data more.

Another technique is "Visidep," where the viewpoint is moved at 4 Hz,
either up and down or left and right, about 2 cm (in virtual-world
scale).  This induces a "kinetic depth" effect.  Unfortunately, my
trials showed that Visidep has a lot of scene motion (you can get
seasick watching it!) and works best with tiny motions on the screen
1/4 visual degree or so).  This means that you need a lot of resolution.
That and the motion sickness problem makes it useless with eyephones
(high FOV implies low resolution, and enhances motion sickness effects).

The final nail in the coffin is that both these methods do not give any
fine depth data to the brain: my trials (admittedly not thorough) showed
that resolution was about 30-40% of distance (as compared to 1-5% for
real stereoscopic images).  But theyre still interesting effects.

--------------------------------------------------------------------------
| My life is Hardware,                    |                              | 
| my destiny is Software,                 |         Dave Stampe          |
| my CPU is Wetware...                    |                              | 
| Anybody got a SDB I can borrow?         | dstamp@watserv1.uwaterloo.ca |
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