I've been meaning for a long while to upload some pics of my semi homebuilt TIR rig. Story is like this. I'd wanted to go with TIR for a long time but my old PC just wouldn't run both AH and a tracking program at the same time so I was out of luck. Built a new PC a couple of years back so now it was a possibility. I bought a TIR unit from someone here and was using the cap reflector clip using the camera in active mode. Using this mode I found I had a little bit of a problem that being the IR lights shining out from the camera would be reflected back by not only the clip which is proper, but also my glasses which isn't! This was a problem when I'd face in certain directions the software would see that other reflection, use it as one of the three it's looking for and skew my view all over the place. It was beyond annoying!
The obvious answer was to just buy a pro clip that had LEDs in it and use the camera in passive mode. This would have worked just fine except for two things. One is after years of my kids trashing my headsets I just use the cheapie Plantronics behind the neck style. They're lightweight and work great for me. The clip is designed to clamp to the side of an over the head type of headset. The other thing is everything I've read everywhere says they're pretty much designed to break. So I thought I'd build something that'd work for me and stand up to some abuse.
One of the programs I'd been messing with in the past was pretty much TIR except you had to build your own stuff to make it work. it was called Freetrack. That gave me the idea to make my own active IR LED ball cap for TIR. I'd have to figure out what I needed to make it happen. I needed a power supply. Probably have a dozen or so old cellphone chargers in a box. Ya never know when this stuff might come in handy! OK so there's a 5vdc power supply. They had a great calculator to figure out the rest here:
http://www.free-track.net/english/hardware/calcled/ . A trip to my local Radio Shack, that had everything I needed to make two rigs for less than $25. So now I'm some wiring, soldering, shrink wrapping and hot glueing away from a finished project.
Started here with my power supply:
A Radio Shack small project box and piece of breadboard make for a nice professional looking job:
I used a piece of coat hangar to stiffen up the rim of the cap. Hot glue held everything in place. Once the sweatband was folded over you can't feel that stuff.
I used three bic pen shafts that were the right size to accomodate the IR LED's. I placed them on the cap as close as I could to the pattern the reflector clip had. Reason was using the camera in passive mode as with the pro clip it looks for a different pattern.
I found in the summer months my head got a little too hot so some slight modifications were in order!
The finished product:
So after all this I found I still had a problem with IR light reflecting from my glasses back to the camera. When using the ball cap clip the camera shines IR light out to the clip. The software is looking for that pattern. In pro clip mode it's not shining light at you as it's looking for the IR LEDs on the pro clip but it's canted sideways on your head and so a different pattern. Another workaround. I made a simple paper mask that blocked the camera's IR LEDs but allowed it's camera a good FOV. It works perfect. I know I could have probably snapped open the camera and put something over the LEDs inside but this worked.
So there ya have it. Been meaning to put this up. Hope it might help somebody with a similar problem. I thought it was a nice little project. I'm actually thinking of making my own pro clip using aluminum tubing.
