From: buckland@ucs.ubc.ca (Tony Buckland)
Subject: Re: Polarized light 3D systems: info wanted
Date: Thu, 16 May 1991 16:32:58 GMT
Organization: University of B.C. Computing Services



In article <1991May15.232536.27134@milton.u.washington.edu> aprile@ghost.
unimi.it (Walter Aprile) writes:

>I hear you have some available info on polarized light 3D systems. I'd
>be really grateful to you if you let me knoz something about this. 
>Enclosed is the posting I planned to put on nn.

 The traditional polarized-light 3-D system is appropriate for
 movies, but not for systems involving viewing computer displays.
 In the case of movies, two separate streams of light are directed
 at the screen, one containing the right-eye image and one the
 left-eye image.  They pass through separate polarizing filters.
 Each audience member's goggles contain correspondingly-oriented
 polarizing filters so that only the right-eye image reaches the
 right eye, and only the left-eye image the left eye, even
 though both photon streams are bouncing off the same place on
 the theatre screen.
 
 The key is the polarization of the photon stream which each eye
 sees.  Achieving this with a computer display would involve
 is to view.  To make a similar scheme work with left-eye and
 right-eye images coming from the same display would involve
 having a mechanical device rotating 90 degrees in front of the
 display every 1/60th second or faster, while the displayto ows
 alternating views for each eye.  This is a big mechanical
 
 What I have seen that works very well is a display that shows
 alternate-eye views at a 120-Hz rate, while each viewer's
 goggles, synchonized via infrared emitted from a small device
 on top of the display, obscure alternate eyes with a switched
 LCD filter; the equivalent of a small round laptop screen in
 front of each eye, with all the pixels switching at once.
 This is an application of polarization very locally within
 the goggle "lens"; is that what you had in mind?  If so, the
 system comes from Silicon Graphics [for whom I do not work,
 and who do not bribe me, and whose stock I do not own, etc].
 Ask about their VGX models; but I'm told the stereo capability
 can be added to vanilla SGI workstations as well.