1. A measurement system for tracking a pose of a physical marker displaceable in a coordinate reference frame, the system comprising: a) the physical marker including a visible target pattern with an arrangement of contrast regions for providing at least two distributed feature points; b) an optical sensor assembly for generating a pair of digital images of the target pattern containing the feature points, the pair of images generated from dissimilar viewing angles; c) a marker template comprising a unique set of reference characteristics including a relationship between the feature points; and d) a processor for testing the pixels of the digital images to determine the spatial location in the reference frame for at least two of the feature points of the target pattern, for comparing the determined spatial locations of the feature points to the set of reference characteristics to confirm the recognition of the physical marker, and for calculating the physical marker pose from the spatial location of the feature points.