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To: narf@hitl.washington.edu
Cc: glove-list@karazm.math.uh.edu
Subject: Re: Interfaces to VR devices 
In-Reply-To: Your message of "Sat, 19 Oct 91 18:53:53 PDT."
             <9110200153.AA10780@milton.u.washington.edu> 
Date: Sun, 20 Oct 91 12:02:17 -0700
From: James Helman <jim@kaos.stanford.edu>
Francis-

At least the Ascension, Polhemus and Logitech devices do roughly the
same thing: measure position and orientation of one or more sensors.

But providing a common interface to all the different gloves on the
market (Mattel PowerGlove, VPL DataGlove, Exos DHM, Virtex CyberGlove)
is another matter.  They all have different numbers and locations of
sensors, ranging from the PowerGlove on the low end to the 22 sensor
CyberGlove on the high end.  Combine this with varying built in
abilities to do gesture recog, internal calibration and force/tactile
feedback and the MIT "all of the above" strategy becomes, well,
challenging.

   The application decides which formats it wants, and informs the
   interface, which provides exactly what is needed.

A good idea in principal, but it would require the interface software
to do things like building a 22 degree-of-freedom hand model from
PowerGlove input (map all to high-end strategy) or only providing a
minimal PowerGlove hand model to all apps (lowest common denominator
strategy).  In the former case, many apps will behave strangely with
the low-end device guessing (better though than not behaving at all),
in the latter, you're throwing away $6K worth of hardware.

A more complex negotiation between the application's requests and the
device's capabilities would be possible, but increases (probably
unacceptably) the complexity both of the interface software and the
app.

I'd love to hear any ideas or progress the HIT lab makes on any of
this.

-jim

Jim Helman					Lab:  (415) 723-9127
Stanford University				FAX:  (415) 591-8165
(jim@KAOS.stanford.edu) 			Home: (415) 593-1233

"The power of the computer is locked behind a door with no knob."
							-B. Laurel