From: daver%sunspot.ssl.Berkeley.EDU@ucbvax.Berkeley.EDU (David Ray)
Subject: Re: TECH:  Alternative Head Trackers
Date: 21 Aug 1992 21:20:35 GMT



In article <1992Aug21.194614.21349@u.washington.edu>
clarke@acme.ucf.edu (Thomas Clarke) writes:

>Does anyone know of (rumors of?) headtracking devices that avoid the 1
>meter cube limitations of Polhemus, Logitech and similar units?
>I am especially interested in systems that don't require a room to be
>specially prepared like the UNC optical system.

You might want to check out the sci.virtual-worlds archives, I believe
the "commercial" section has some info on different head-trackers.
They generally use one of 4 methods -- magnetometer, inertia,
ultrasonics/radio, optical.  The ultrasonics and optical types
physically transmit to a reciever, so the head position is limited to
the signal's range and resolution.  The magnetometer and inertia type
head trackers *in principle* should not be restricted since the
sensing mechanism is self-contained. In general the HMD's that use
these are VERY expensive.

I have been researching and planning to build a "low-cost" HMD that
uses magnetometer or inertial sensing to transmit a mouse-type signal
to a Mac ADB and/or a PC's mouse port. The idea is to just substitute
the HMD for the mouse in order to simplify the interface. If I have
any reasonable success with this I'll post it in this newsgroup.

Somebody (Bernie Roehl?) recently posted about a HMD that they made
from a network of LED's and CCD cameras. It was low cost compared to
commercial products and had really good resolution, less than 1 degree
if I recall. But the sensing mechanism did limit head position.

-dave