Laser Multitouch Surface

This is an inexpensive way to turn any surface into an input device that senses the x & y position of multiple simultaneous touch points. The hardware necessary is easy to find online by following the links below, or at a well stocked electronics store: a webcam, two mountable lasers, a power source for the lasers, and something to prop up the camera with. This is not a true multitouch surface, but it is an inexpensive and useful alternative.

There are innumerable uses for a multitouch surface; the software includes one simple audio application. Each finger controls an oscillator with the y-position mapped to volume and the x-position mapped to frequency. The software can also pick up the lean of the fingers using the aspect ratio of the laser beam across the finger. When a finger is perpendicular to the surface, the height of the laser beam across that finger is smaller than when a finger is pitched back. This adds another parameter of control, which, in the included software, is mapped to a timbral change using FM synthesis.