The Virtual Air Guitar project developed at the Helsinki University of Technology finally gives friends of true rock fans what they have been looking for - a way to hear what is going on when the true fan plays their 'air guitar'.
The Virtual Air Guitar system consists of a video camera, a computer running computer vision software and (of course) heavy-duty speakers. The erstwhile rocker puts on a pair of brightly colored gloves; the computer vision software tracks the movements of the hands and detects different gestures.
As you move your left hand along the neck of your 'instrument' the computer runs through the scale. Hammer-ons and blues bends are both supported. The guitar sounds are based around the pentatonic minor scale - favored by rock soloists. Check the video:
In his classic 1975 novel Shockwave Rider, the always-prescient John Brunner writes about coley, a musical form that requires no visible instruments.
...he found a coley group, all blue-skin makeup and feathers in their hair, not playing instruments but moving among invisible columns of weak microwaves and provoking disturbances which a computer translated into sound... hopefully, music.
(Read more about John Bruner's coley group)