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From: halazar@mit-amt.MEDIA.MIT.EDU (Michael Halle)
Newsgroups: comp.graphics
Subject: Re: 3d Computer Generated Holography
Message-ID: <589@mit-amt.MEDIA.MIT.EDU>
Date: 24 Aug 89 23:41:19 GMT
References: <441@ctycal.UUCP> <1306@blackbird.afit.af.mil>
Organization: MIT Media Lab, Cambridge, MA
Lines: 50
In-reply-to: news@blackbird.afit.af.mil's message of 24 Aug 89 17:13:37 GMT


Your summary is correct.  The work we are doing here at MIT (under
Steve Benton) generally uses computer graphics to make the images, and
then lets "Mother Nature" do all the hard stuff (figuring out the
holographic fringe pattern formed on the image of the film).  Even
more work is saved by eliminating vertical parallax in the final image.
In other words, the object in the hologram will move naturally as the
viewer moves side to side, but will not change in perspective as the
viewer moves up and down.

Traditional, hard-core CGH forces the computer to bear the cost of
determining which fringe goes where.  Much more time is spent
computing the image then actually composing it.  That's because of the
cost of computing the fringe pattern is proportional (polynomially,
usually) to the complexity of the image (how many points are in the
picture).  In a holographic stereogram, the cost is constant.  We
generally render between 100 and 1000 side to side views of an object,
each view anywhere from 640x480 pixels and up.  Holograms made from
these images are full color and white light viewable "snapshots" of
any sort of three dimensional computer graphics.  Size for our work is
typically 20x25 cm, but can be up to about 1m square.  We are also
working on ways to make the image dynamic, in the spirit of 3D video.

Our research is a combination of making better holograms and exploring
uses for them.  CAD/CAM and medical imaging are two of our major foci.
We hope that by introducing people to the technology now, we can help 
holography be widely useful by the time technology and funding permit
high quality images to be mass-produced quickly.

Here's a couple of holographic stereogram references:

@inproceedings{benton:sur,
author = {Stephen A. Benton},
title = {Survey of Holographic Stereograms},
booktitle = {Processing and Display of Three-Dimensional Data},
year = 1983,
organization = {SPIE} }

@inproceedings{benton:pho,
author = {Stephen A. Benton},
title = {Photographic Holography},
booktitle = {Optic in Entertainment},
year = 1983,
organization = {SPIE} }

If you are interested in further information, let me know.

						--Michael Halle
						  Spatial Imaging Group
						  MIT Media Laboratory