VIDEO CAMERA BASED COMPUTER INPUT SYSTEM WITH INTERCHANGEABLE PHYSICAL INTERFACE

A computer input system and method is described which includes a spatial reference member having a body with a first surface and an opposing second surface. The spatial reference member separates a first spatial region including the first surface from a second spatial region including the second surface. A physical object is movable within the first spatial region. Optical indicia tracks the physical object through the body. The optical indicia is observable from the second spatial region. An optical detector positioned in the second spatial region tracks the optical indicia and develops signals which may serve as inputs to a computer. The object may emit a signal which is tracked by the optical detector.