Path: utzoo!attcan!uunet!mailrus!news-server.csri.toronto.edu!dgp.toronto.edu!mccool
From: mccool@dgp.toronto.edu (Michael McCool)
Newsgroups: comp.graphics
Subject: Re: TIs 3D Display
Message-ID: <1990Oct1.143245.753@jarvis.csri.toronto.edu>
Date: 1 Oct 90 18:32:45 GMT
References: <1990Oct1.160621.5445@infonode.ingr.com>
Lines: 41

palmerc@infonode.ingr.com (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.

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

TI had a demonstration of this at SIGGRAPH this year.  It was very 
impressive, but has drawbacks.  It works by scanning a laser over
a rotating double helix of plexiglass (or something) coated to "stop"
the laser beam and produce a dot in space.  The relative timing of
the laser illumination and the rotation of the helix determine the
height of the spot.

Make that a 2' diameter sphere, with a 5^3" working space to 
one side.  The center can't be used; the axis of the helix is there
(singularity).

It is like the old calligraphic displays, except it is even more
limited: it can only display points in space.  I guess the computation
to scan a "line" would be too nonlinear and would have singularities
at some orientations of the line (such as vertical). Like calligraphic 
displays, there is a limit on the number of points that can be displayed 
while still avoiding flicker.   There is a flicker anyways from the limit 
on the rotation speed of the helix (noisy, too, but with a neat,
science-fictionish OMMMM sound that fits, somehow).  Color is 
possible by having more than one laser, and having them scan independently:
multiply the cost of the system by 3.  Multiple lasers can also be
used to decrease flicker by having them scan points in parallel.
The display was also a little blurry, since the disk needs a finite
thickness and invariably disperses the laser point a bit.

Of course, some phenomena are impossible, such as opacity and
reflectance.  Not a replacement for 3d computer graphics.

I have nothing to do with TI, I just went to their booth and 
asked annoying questions 8-) 

michael mccool@dgp.toronto.edu