A three-dimensional position and orientation tracking system comprises one or more pattern tags, each comprising a plurality of contrasting portions, a tracker for obtaining image information about the pattern tags, a database with geometric information describing patterns on pattern tags and a controller for receiving and processing the image information from the tracker, accessing the database to retrieve geometric information, and comparing the image information with the geometric information. The contrasting portions are arranged in a rotationally asymmetric pattern and at least one of the contrasting portions on a pattern tag comprising a perimeter with a polygonal shape. The pattern tags may be borne on tracking markers that have a three-dimensional shaped surface. The tracking system can be implemented in a surgical monitoring system in which the pattern tags are attached to tracking markers or are themselves tracking markers. A method associated with the system employs the rotationally asymmetric patterns on the tags to determine the three-dimensional locations and orientations of items bearing the tags using non-stereo image information.
