FreeTrack Forum

Building a Point model device

After playing with the Tracking system a bit I'm thinking:

1. Your head pivots at the neck, it would be best to have LED points placed with pivotal point of LEDS directly over center of your neck if possible.  This could be done with a hat with a headset etc.

2.  You would want the LEDs visable all the time to the Webcam through out the range of head movement you determine to use.

3.  To avoid any potential visual problems with your eyes you would want the LEDs physically impossible to see or expose your eyes to the light from the LEDS in any position your head travels.

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Considering all of the above as requirements what would be a best way to configure the placement of the LEDs on the point model?

I Would assume a reverse 3 point horizontal clip (with center one bulging out) and modification of the software to allow for this type of tracking.

1. Actually Freetrack (and TIR also) takes advantage of the fact the leds (or reflecting surfaces) are a bit away from the pivot axis of your neck as it gives more radius and thus a wider movement to the LEDs and better tracking. That's why they use a Cap and not a Hat. Imagine how the tracking would be if the top led will be precisely on the pivot axis... The led don't move so freetrack can't calculate the movement as there is no apparent movement in the camview...

I build a tracker with LEDs closer together and closer to the forehead and is working perfectly.

2. LEDs closer together and a wider FOV camera do the trick.

3. TIR has IR leds mounted and emitting in the thing. Some webcams have LEDs too... there is no problem I think.