1. A system for tracking the pose of an object displaceable in a coordinate reference frame, the system comprising: an optically-visible target pattern on an object being tracked, the pattern containing a plurality of 2D contrasting shapes, the contrasting shapes arranged so as to uniquely differentiate the pattern from other patterns; an optical sensor assembly spaced apart from the object, the optical sensor assembly located and configured to capture images of at least a portion of the pattern, the sensor assembly configured to generate at least a pair of 2D images of the portion of the pattern, each 2D image being at a different viewing angle of the portion of the pattern than the other 2D image(s); and a processor for retrieving stored data for a plurality of distinct patterns, including for each distinct pattern, a set of 3D coordinates of optically identifiable defined points based on the arrangement of the contrast shapes in the pattern, the processor configured to receive the 2D images of the portion of the pattern from the sensor assembly and to identify one of the distinct patterns in the 2D images based on the correlation of the contrast shapes in the 2D images with the stored data, and the processor configured to locate defined points in the 2D images and use a transform to determine the pose of the object based on the located defined points in the 2D images and the 3D coordinates in the stored data for the identified distinct pattern.