Patent ID: 7317482

Claim:
A method for calculating a distance from an optical axis of an imaging device to an input point, comprising: approximating the input point with an arbitrary polygon with eight or more sides centered on the optical axis of the imaging device; calculating a distance between a point corresponding to the optical axis of the imaging device and the input point as a function of the arbitrary polygon; determining a value x representing a distance between the point corresponding to the optical axis and the input point along an X axis; determining a value y representing a distance between the point corresponding to the optical axis and the input point along a Y axis; determining constant coefficients A and B; and calculating the distance between the point corresponding to the optical axis and the input point as approximately equal to (x+y)+A*abs(x−y)+B*[abs(2x−y)+(x−2y)], wherein abs( ) is an absolute value function.