Patent ID: 7932899

Claim:
A position detection system comprising: a first optical unit configured to image a space; a second optical unit configured to image the space; a memory; and a processing device interfaced to the memory and the optical units, the processing device configured to: access image data from the first and second optical units; iteratively determine at least one of a current first touch position and a current second touch position using the accessed image data; in one iteration when both the current first touch position and the current second touch position are determined using the accessed image data: define, in the memory, a polygon based on the current first and current second touch positions, the polygon having at least four sides; and in a subsequent iteration when only one of the current first touch position or the current second touch position is determined using the accessed image data: access the polygon as previously defined in the memory and use the current first touch position or the current second touch position determined using the accessed image data, and the previously-defined polygon, to estimate the other touch position that was not determined using the accessed image data.