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From: bhoughto@pima.intel.com (Blair P. Houghton)
Newsgroups: comp.graphics.visualization
Subject: Re: HOLOGRAPHIC VISUALIZATION
Message-ID: <1783@inews.intel.com>
Date: 16 Jan 91 18:11:52 GMT
References: <1991Jan15.233942.21236@wam.umd.edu>
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In article <1991Jan15.233942.21236@wam.umd.edu> jonnyg@wam.umd.edu (Jon Greenblatt) writes:
>
>	Has anyone heard of some type of technology to produce holographic
>images from a computer generated holographic pattern. I can think of
>two ways of doing this right now, the second being the most likely.

It's called pscholography.  CNN had a bit on this the day after
I bought a small pscholograph for a friend for christmas.

A pscholograph is a high-tech version of those "magic
pictures" you used to get as Cracker-Jack prizes.  A
computer generates a 3-D situation, which is then
represented by projecting it onto visual planes at every
few degrees of rotation.  The images are then shone onto
the film at the corresponding angle.  Covering the film is
a diffraction grating with linewidth/linespacing large
enough to prevent diffraction of external visual light
(which would overwhelm any image transmitted from teh
film); the basic reason for using a diffraction grating is
just to get many, many, many images onto the film.  I.e.,
the plastic-toy ones would only change the image every 30
degrees or so, allowing only a few images to be stored.
With the smaller linespacing, however, the images can
change every few tenths of a degree.  The larger linewidth
blocks out all the other images.  Diffraction may serve to
blur the lines together.

3-D effects are generated by parallax; your left eye simply
sees a different picture from the one your right eye sees.

Motion can be stored.  The one I bought had both the 3-D
and motion.

The quality of the cheap ones isn't terriffic.  Vertical
registration was poor, so adjacent images didn't quite
line up, and the picture bounced.  The CNN story showed
some really nice ones, printed on media several feet across.

				--Blair
				  "How far across is the electronic medium?"