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From: ncramer@bbn.com (Nichael Cramer)
Newsgroups: comp.graphics
Subject: Re: TIs 3D Display
Message-ID: <59765@bbn.BBN.COM>
Date: 2 Oct 90 21:55:21 GMT
References: <1990Oct1.160621.5445@infonode.ingr.com> <1990Oct2.190558.14773@vicorp.com>
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Reply-To: ncramer@labs-n.bbn.com (Nichael Cramer)
Organization: Bolt Beranek and Newman Inc., Cambridge MA
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ron@vicorp.com (Ron Peterson) writes:
|palmerc@infonode.UUCP (Chris Palmer) writes:
|>I read a very small blurb about Texas Instruments new 3D bubble display
|>that creates a 3D image in a 2" diameter sphere.  The image is viewable
|>from any angle without special lenses or glasses.
|I read about a 3D display in EETimes that I think had been built by TI.  It
|was a plastic hemishpere that enclosed a clear plastic disk or ellipse that
|rotated at high speed and was drawn onto with a laser beam or bright light.
|The image with this kind of approach is viewable from any angle without
|glasses or special optics.  The picture showed a bubble about two feet
|across.  It was being demonstrated at some convention like SIGGRAPH.

I saw this at SIGGRAPH.  Your description is basically correct except that
I believe the shape of the rotating sheet was a helix.  Therefore the
height of the point of light was determine by (and limited to) the height
of the helix.  In cross-section:
                      
           Axel -------->XX
                         XX
                         XX===========*=============  <--- Cross-section
                         XX           o                   of Helix
                         XX           o
                         XX           o
 ========================XX           o
                      	 XX           o
                      	 XX           o
                      	 XX           o
                                      o
                                     -o-
                                     | |
                                     | |
                                     | |
                                 Laser Source


|>>Question:  How does it work?  What is the image quality?  Is real-time
|>	   animation possible?  Is it color?

Well, basically what you have is a vector-drawing system, with all of its
inherent limitations (e.g. no surfaces, etc).  The limiting factors for the
image quality and speed/quality of animation are "pixel" resolution size of
the material of the rotating sheet and refresh rate (i.e. how fast can you
get a two-foot diameter sheet of plastic rotating like this).  Re color,
etc., you could presumably add more than one laser.

Another (vaguely) related system is BBN's SPACEGRAPH system [yes I work
here, but I'm not related to the SG group so, this isn't really an
advertisement.  Honest].  In the case of SPACEGRAPH the lasers beams are
drawn onto a mirror whose center is rapidly vibrating.  This has the same
advantages of "equipment-free" 3D viewing without the mechanical hassles of
the large body movement and the image size is not limited by the physical
size of the helix.

NICHAEL  
nichael@bbn.com  --  "This is my Email to the world..."