Sensor systems for interactive surfaces

This paper describes four different systems that we have developed for capt uring various manners of gesture near interactive surfaces. The first is a low-cost scanning laser rangefinder adapted to accurately track the positio n of bare hands in a plane just above a large projection display, The secon d is an acoustic system that detects the position of taps on a large, conti nuous surface (such as a table, wall, or window) by measuring the different ial time-of-arrival of the acoustic shock impulse at several discrete locat ions. The third is a sensate carpet that uses a grid of piezoelectric wire to measure the dynamic location and pressure of footfalls. The fourth is a swept radio frequency (RF) tag reader that measures the height, approximate location, and other properties (orientation or a control variable like pre ssure) of objects containing passive, magnetically coupled resonant tags, a nd updates the continuous parameters of all tagged objects at 30 Hz. In add ition to discussing the technologies and surveying different approaches, sa mple applications are given for each system.