Why pink? Wouldn’t any chromakey color work? White under UV would stand out. There’s also the Theremin angle as well, although I’m not sure it is more than two dimensional in sensitivity. Got any links to previous attempts?
I was half-joking about the pink glove. But in seriousness, if you can use a distinctively colored marker on his hand, you can use a combination of jit.chromakey @mode 1 and either jit.findbounds or the cv.jit objects to keep tabs on it.