From: uselton@nas.nasa.gov (Samuel P. Uselton)
Subject: Re: Direct Neural Input (Was Re: VR Oneupmanship ?)
Date: Mon, 28 Oct 91 19:36:53 GMT
Organization: NAS Program, NASA Ames Research Center, Moffett Field, CA


In article <1991Oct26.040441.17010@milton.u.washington.edu> craig@utcs.utoronto.ca (Craig Hubley) writes:
>
>In article <1991Oct20.192343.1005@milton.u.washington.edu> jdb9608@ultb.isc.rit.
>edu (J.D. Beutel) writes:
>
	(lots of good stuff deleted)
>
>>link when you could put video monitors on glasses instead?  
>
>I would be interested in starting a discussion on the optics of this,
>especially if you wanted to let part of the real world shine through.
>Is it possible to project light from angles that simulate the virtual
>objects being at a specific distance, say, one meter from the eye ?
>
	The first (unclassified) head mounted/tracking display system
	(that I know of - earlier refs welcome) done by Ivan Sutherland
	and friends at U. Utah in the late 60's or early 70's used 
	displays at the side of the head and glasses with half silvered
	lenses which reflected the displays to the user's eyes.  
	A wireframe image was superimposed on the "real world" seen
	through the glasses.  Since the displays were separate for each
	eye, the basic computation was the same as for ordinary stereo
	with the extra reflection added in.  The stereo disparity 
	controlled the apparent distance of objects.

	When I was in grad school, a fellow grad student, Don Fussell,
	under Henry Fuchs' direction, set up a similar system but with
	raster CRT's and short range broadcat TV instead of cables.
	Tracking was to be done with LED's on the helmet and (early)
	1-D CCD arrays to detect planes containing the lights.
	The CCD resolution wasn't good enough at the time (late 70's)
	and the helmet looked hilarious, buyt the principals clearly
	worked.

	The first Chapel Hill system also used temple bar mounted CRT's
	and 1/2 silvered lenses, superimposing wireframe images on the 
	real world.

	The images look "ghostly" because you do see the world "through"
	things rendered.  I don't know how satisfactory that would be,
	or how to avoid it.  (The other option, of course, is to digitize
	the "real world" and include it in the virtual environment.)


	lots more deleted..........

>
>>J. David Beutel  11011011  jdb9608@cs.rit.edu      "I am, therefore I am."
>
>Craig
>-- 
>  Craig Hubley -- Consultants in object-oriented technology & techniques, --
>  Craig Hubley & Associates -- user interface design & user productivity  --
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Sam Uselton		uselton@nas.nasa.gov		ex-prof
employed by CSC		working for NASA (Ames)		speaking for myself