Method of estimating position of writing nib relative to an optical sensor

摘要

A method of estimating a position of a point on a writing implement relative to an optical sensor mounted on the writing implement is provided. The method comprises the steps of: (a) placing the point in contact with a coded surface; (b) capturing, using the sensor, at least two images of the coded surface at different rotations of the writing implement relative to the surface; (c) determining, from a perspective distortion of the coded surface in each image, an estimated rotation and viewing distance for each image; and (d) estimating, from the estimated rotations and viewing distances, the position of the point relative to the optical sensor.