Hand/finger tracking system

A curious hand/finger tracking system is described in Smart Laser Scanner for Human-Computer Interface by Alvaro Cassinelli, Stephane Perrin & Masatoshi Ishikawa

The next logical step would be to remove the need for any (dedicated or merged) input space, as well as the need for any additional input device (stylus, data-gloves, etc). This would allow inputting data by just executing bare-handed gestures in front of a portable device - that could then be embodied in a keyboardless wrist-watch. (...) We are currently studying a simple active tracking system using a laser diode (visible or invisible light), steering mirrors, and a single non-imaging photodetector, which is capable of acquiring three dimensional coordinates in real time without the need of any image processing at all. Essentially, it is a smart rangefinder scanner that instead of continuously scanning over the full field of view, restricts its scanning area, on the basis of a real-time analysis of the backscattered signal, to a very narrow window precisely the size of the target.

Lots of video demo!

Why do I blog this? working on the user experience of tangible interfaces, I am interested by such new interactions styles.