From: pipercub!fenwick@clipper.ingr.com (Steve Fenwick)
Subject: Re: Cheap head-mounted display
Date: Thu, 16 May 91 16:54:51 GMT
Organization: Intergraph Advanced Processor Division - Palo Alto, CA



In article <1991May16.055148.2358@milton.u.washington.edu> cdshaw@cs.ualberta.ca
 (Chris Shaw) writes:

|> Steve Fenwick :
|> >In article cdshaw@cs.ualberta.ca (Chris Shaw) writes:
|> >>The noisiness of the data given by the ultrasound sensors will drive you 
|> >>wild.
|> >>You'll probably have to use a Polhemus Isotrak for head tracking.
|> >
|> >You're tarring the whole technology with a too-broad brush.  Ultrasonics
|> >can be used for reliable 2-d and 3-d positioning; I've done it.
|> >Steve Fenwick
|> 
|> Perhaps I am, perhaps not.
|> 
|> The original post in this thread suggested that the Power Glove ultrasonic
|> trackers be used for head tracking. This means that you need to track
|> position and orientation, at all attitudes (no dead spots). For head tracking
,
|> the data should also be low noise, else the jitter will "drive you nuts".
|> Ultrasonics are probably ideal for position-only tracking, but currently the
|> powerglove will give only roll-of-forearm data, and will only work when 
|> your arm is facing the sensor array. Of course, you COULD use this to detect
|> head-turn +/- 90 degrees, but that's all. No looking up or down with this 
|> setup. 
|> 
|> Ultrasound is certainly worth looking into, though, because it's got a 
|> big price advantage.

Serves me right for jumping into the middle of a thread!  I assume the
powerglove you're talking about is the Nintendo glove.  I can't agree about
the roll-of-forearm only, since it seems to pick up pitch, yaw, and one axis of
translation (at least when my cousin/video-game addict uses it!)
This holds with what I found out in my project, which seems to have been
exactly the same as the powerglove, but wearing the three sensors instead
of the transmitter.

You're right, in that the three receiver/one transmitter scheme won't
let you pick up absolute 3-d position and attitude;  it will give
you three easy-to-use degrees of freedom (pitch, yaw, one translation),
and can thus be used a a 3-d control.

I was working on this in 1987, well before the glove came out,
and the project was based on a 1986 Mac mouse replacement (head-mounted;
lots of apps for handicapped.)  Contact Dr. Mark Friedman at Carnegie-Mellon
for more details.

P.S.  I tried replying to your mail, Chris, but it bounced locally.

fenwick@clipper.ingr.com        +-----------------------------------------+
Intergraph APD, 2400 Geng Road  | PP-ASEL-IA at last! Let's bust a cloud! |
Palo Alto, California  94303    +-----------------------------------------+
(415) 852-2325/494-8800         
-- 
fenwick@clipper.ingr.com        +-----------------------------------------+
Intergraph APD, 2400 Geng Road  | PP-ASEL-IA at last! Let's bust a cloud! |
Palo Alto, California  94303    +-----------------------------------------+
(415) 852-2325/494-8800