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From: carl@bdaemon.UUCP (carl)
Newsgroups: net.periphs,net.research,net.graphics
Subject: Re: volumetric displays
Message-ID: <306@bdaemon.UUCP>
Date: Fri, 27-Sep-85 23:16:57 EDT
Article-I.D.: bdaemon.306
Posted: Fri Sep 27 23:16:57 1985
Date-Received: Wed, 2-Oct-85 00:25:33 EDT
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Demonstration models of volumetric displays using vibrating mirrors,
rotating screens or similar concepts have been around for a long, long
time.  One of the first I saw was in 1962 at the ITT Labs in Nutley, N.J.
Static 3D displays were common at the turn of the century and the subject
of a fair amount of research by perceptual psychologists at the time.

The reason why we have seen many demonstration devices and no production
displays is very simple - the huge bandwidth required.

Consider the case where ordinary television resolution is acceptable:

	1. A 2D picture, just like your vanilla TV, requires about 3 MHz
	   for about 300 line resolution.

	2. For a 3D picture with about 300 planes in the Z axis the
	   bandwidth would have to be 3*10^6 * 300 or 900 MHz, a non-trivial
	   accomplishment for a display with limited useful applications
	   (Would you really like to have an air-controller control *your*
	   flight with a standard TV quality display?).

Obviously, resolution is a function of the third power of the bandwidth, so
I am not going to hold my breath waiting for practical 3D displays to become
reality.

Yours for an appreciation of what simple arithmetic can do for old,
time-worn ideas.

Carl Brandauer
daemon associates, Inc.
1760 Sunset Boulevard
Boulder, CO 80302
303-442-1731
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