A spinning vertical shaft with two strobe lights connected to an ultrasonic range detector. When a person comes within range, the strobe flashes at him/her every revolution. If he/she moves around, the flash will follow. A modulated laser draws circles on the ground to attract viewer/participants. Flash can also be set to flash at regular intervals. In this mode, participants can change the speed and direction of spinning, resulting in pseudo-random or slowly processing flashes.

Built for BurningMan 2001 (these photos were taken somewhere greener)