Subject: Re: Re: Body Tracking

From: [email-masked]
Date: 25 May 94 15:09:28 EDT

>Thought of using Doppler radar? Most units can track a man sized object at 
10m,  >and only cost about >USD50...use two and do triangulation to find 
out where the  >body is...

My only concern would be the speed of the samples.  How fast can it 
calculate?  How about accuracy?  I would image such a system would need to 
be accurate to an inch or two.  I don't think drift would be a problem with 
radar.  With a 10 meter range, you could have virtual sporting events.

Some of the ways that I have thought  or seen for tracking a body are:

Cameras mounted on the helmet, like those at UNC, and a series of infra-red 
LEDs in the cieling.  The response time is excellent but you loose tracking 
if you tilt down more than 20 degrees.  The cameras are heavy also but with 
new versions that should not be a problem.  

I checked on optical gyroscopes.  These little units run about $3000 a 
piece and can give you fairly accurate readings.  The sample rate is also 
good.  The units themselves run anywhere from 1lb to 3 lbs.
A gyroscope hooked up with an accelerometer might do it, but now the 
technology is just too bulky and expensive.

Dave Stampe used an infra-red tracking system, but said that the range 
wasn't that good.

I took a power glove and mounted it like the Logitech head tracker, I got a 
better range than the logitech, but the rotation is crummy and the range is 
still limited.  Alot of noise also.

I have been working with some other individuals on developing a "grid" of 
ultrasonic transmitters that would allow the user to move about in an area 
only limited by the size of the grid.

The new flock of birds with the extended range for one transmitter gives me 
an effective range of about the 16' diameter that I was looking for, but 
just for one unit the cost is upwards of $7000.

I have looked at the supermarket scanners and thought that there must be a 
way to use a large version of that to track someone.  Maybe three barcode 
stickers on the HMD? :-)

I considered a head tracker that was actually a chin tracker where you 
would have a small sliding tube attached to a chin strap.  This with a 
special kind of potentionmeter, you could read head tilt.  And a 
potentiometer attached to the other end could give you rotation.  This is 
great for a stationary system, but it still does'nt solve the problem of 
body tracking.  The advantage of this system is a greater range of rotation 
sampling.  Your chin moves much more than the center of your head by your 
ears.

I think that the ultrasonic system will ultimately be the least expensive 
to build.  Its just that I have to find someone who knows ultrasonics and 
is willing to develop the tracker.

I am developing a VR game called Virtual Knight.  I have already built a 
stereoscopic  HMD with two active matrix LCDs.  The unit has an open top 
for comfort and air.  It weighs about 3.5 lbs and has about a 35 degree 
FOV.  There is no focus or ocular distance adjustment necessary.  Just put 
it on.  BTW, you can wear glasses with it.  I have built an ultrasonic 6DOF 
joystick where the transmitter is mounted on your chest.  It works 
incredibly well.

The player will be in a 16 foot arena.  In front of you is a knight.  As 
you approach the knight, he swings at you.  Your joystick is your virtual 
sword.  You will gain points by how well you battle him.  Ultimately the 
body tracker will be very important.  Currently I just have a head tracker 
and move by a small thumb joystick.  The entire game is based on VR386.  
With a Dual Lightning VGA card to drive the separate images, we can get 
nearly SGI workstation speed.> 30 frames/second in each view on a 486/66.

I need some help, I have done all I could.  I am not a programmer and I 
have reached the limits of my abilities as far as that goes.  I need 
someone who can program specific code for VR386, such as collision 
detection, scoring, and sound.  I also need someone who can build the 
ultrasonic system.

I will be releasing the early prototype at the Discovey Zone in Raleigh, 
N.C. around late June if all goes as planned.  We will be seeing how well 
the equipment holds up and also what kind changes we need to make for a 
distribution version.  

I'm hoping that if all goes well, we will be able to secure an investor(s) 
that will let us be able to pay for a more advanced system.  

When it is all said and done, this game is designed to be sold to the 
arcade market, ala W Industries.
The final list price should be no more than $25,000 for the entire system.  
Through a link, we will be able to hook up two of the units where the 
knights can be real people.  

If you are interested, or have any ideas or any connections please e-mail 
me.  I want to get a solid direction on this by this year's end.  

You can reach me at  [email-masked]

---

From: [email-masked]
Date: Thu, 26 May 94 10:51:55 +0100

Hi !

My name is Darko Katovic and I living in Zagreb, Croatia.
At this moment I'm student on Faculty for physical education. 
 
One of our research tim work on the colecting all information about
VR. 
We find your project interesting and if it's possible please send us
more information or demo's.

Thanks

                                                        Darko