here’s one speculative approach. since you re using the kinect you can have it analyse the scene and look for people, users in kinect terms. no calibration is needed for that so people can walk freely in and out.

there’s a function in the kinect libraries called getuserpixels or something similar. it will return from the rgb image the pixels that ‘belong’ to a user. substract that from the image and you’ve removed the people from your scene. do your tracking on that.

max externals for kinect and apps like synapse and osceleton don’t have this functionality (AFAIK). if you’re, like me, not much of a code ninja i’d advise looking into simpleopenni for processing. it exposes the openni and nite libraries in processing, much easier than doing the whole linking and compiling business in xcode, visual studio and the like.

well an entirely different approach would be to coat ‘m with IR reflective paint or something. use a IR sensitive camera (cheap webcams are, just need to remove their IR filter, replace it with a high pass filter that only lets through IR. expose the threads to IR light and there you go…

this doesn’t tell you how to track their shape though. not sure about that.

btw, a kinect projects a whole lot of IR rays from one of its lenses and has an IR cam built in. many apps including the jit.freenect.grab external let you read out the IR image. you’d wanna make sure your tracked threads are a lot more reflective than the rest of the scene so you can easily filter it out.