Video pose tracking system and method

Abstract

A measurement system for tracking a pose of an object displaceable in a coordinate reference frame, such as a three dimensional coordinate system. The system comprises a predefined physical marker adapted for rigidly coupling to the object. The marker can be two or three dimensional in shape. The marker includes a visible target pattern with a series of contrast regions for providing at least two distributed feature points. The contrast regions include an arrangement of alternating dark and bright regions defining an intensity saddle point at their intersection. Each feature point is located at a respective intensity saddle point. The system also has an optical sensor assembly for generating a pair of digital images of the target pattern containing the feature points, wherein the pair of images generated are from dissimilar viewing angles. The system also has an identifier for testing the pixels of the digital images to determine the spatial location in the reference frame for each of the feature points of the target pattern. A marker template including a set of reference characteristics is used to uniquely define a pose relationship between the features points. Further, a processor is used for comparing the determined spatial locations of the feature points to the set of reference characteristics to confirm the recognition of the predefined marker. A method is also described to identify the intensity saddles contained in the digital images.

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