From: dtj@sumac.cray.com (Dean Johnson)
Subject: Re: VR hardware questions
Date: Mon, 24 Jun 91 17:46:20 CDT



In article <1991Jun24.195408.13585@milton.u.washington.edu>, mark@cs.ualberta.ca (Mark Green) writes:
> 
>In article <1991Jun24.153351.13571@milton.u.washington.edu>, dtj@sumac.cray.com 
> (Dean Johnson) writes:
>  
>> Since pounding on the moderator (sorry Bob!) about the lack of "reality" in
>> this Virtual Reality group, I realized that I have done little help the 
>> situation. It is now time for me to stop bitching and start working!
>> 
>> 1. Does anybody have any idea what the cost of a plain Polhemus emitter (the
>>    thing on the top of the eyephones) costs all by itself, not including the
>>    boards, etc. that go with it? I am trying to get a handle on what it would
>>    cost to prototype other devices, presuming that you have bought atleast
>>    one "full boat" system.
> 
> I'm not sure why you would want this.  The source and sensor are relatively
> easy to fabricate.  The Polhemus itself is relatively old technology
> and could be improved greatly if it was reimplemented using current
> handware devices.  For the technical details on the Polhemus see the
> Sept. 1979 issue of IEEE Transactions on Aerospace and Electronic
> Systems.

Because I know little or nothing about hardware and the underlying technology,
but I'm hoping that it would be trivial to mount an emitter on something other
than an eyephones unit. I am looking at the polhemus as a black-boxe and I 
want to staple them ;^) to something else. Additionally, I am hoping that using
existing mechanisms, the amount of programming (and debugging) is minimal.
>From a totally hardware naive perspective, if reimplementing the polhemus
in newer technology was easy, why hasn't someone done it? At least I haven't
seen it done. I don't mean that to sound like I am being critical of the
statement, but I do express my skepticism. Thanks for the reference, it gives
me somewhere to start working on opening the blackbox.

> 
>> 2. Does anybody have any experience with drivers and interfaces to the 
>>    dataglove, other than through the Macintosh and "Body Electric". Someone 
>>    *has* to have tried to hook it up to a Sun or something like that. Even
>>    instances where you hit a "show-stopper" is of great help. Perhaps we
>>    can get a collaborative effort going for the DG like is going on with
>>    the PowerGlove.
> 
> For several years we have used a client-server model for driving the
> DataGlove.  One process runs on one of our SGI workstations and interface
> with the DataGlove using the standard serial protocol.  This process
> handles all the low level details of the interaction with the DataGlove.
> The user process uses a subroutine library to communicate with the
> server process.  The user program can reside on any of the workstations
> on our laboratory.  Communications between the two processens is through
> TCP/IP over an ethernet.

Yep, that is exactly what I am interested in! Having done that, have you
seen any improvement in the speed in interacting with the world? I guess
what I am looking for is whether or not the Mac is a bottleneck to the 
overall system? This leads to question of world building and controlling
software, did you "roll your own" or are you using some commercial package?

-- 
	-Dean Johnson
	 Software Berserker/Rabid-Prototyping Specialist
	 Tools, Libraries, and Commands Group
	 Cray Research Inc.	  Eagan,MN	(612) 683-5880


[MODERATOR'S NOTE:  Do I detect some value to the newsgroup?  Hmmm?  ;-)]



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