Patent ID: 7269531

Claim:
A method of determining the time-varying absolute position of a device with respect to a surface having a position-encoded portion and an obscured portion, wherein the position-encoded portion bears accessible encoded position data and the obscured portion does not bear accessible position data, the method comprising the steps of: moving the device with respect to the surface; measuring a time-varying vector representing the relative movement of the device over the position-encoded portion and the obscured portion of said surface during motion of the device; measuring at least one absolute position of the device with respect to the position-encoded portion of said surface during a portion of said motion when said position-encoded portion of said surface is accessible; initializing the position of the vector to the at least one absolute position measurement thereby measuring the absolute position of the vector and thus the time-varying absolute position of the device; and recording the measured time-varying absolute position of the device for subsequent outputting to an interpreter mechanism.