Patent ID: 6556722
Filing Date: 2003-04-29
Classification: G01S,H04N

Abstract:
A method of determining the three-dimensional position of an object in a reference frame, the method comprising:providing three or more markers at respective reference positions, at least three of the markers being patterned as a series of concentric shapes encoding a plurality of bits of identification information in the darkness or color of the shapes, the center of the concentric shapes of each patterned marker providing a reference point for each marker, wherein each marker has a respective distance from a reference plane of the reference frame, the distances varying between the markers; storing information including a measure of the three-dimensional positions of the markers in the reference frame and information identifying the patterned markers; obtaining an image of at least a sub-set of said markers from a camera associated with the object; processing the image to identify the positions of said markers in the image and, for each patterned marker in the sub-set, identifying the respective reference point and decoding said identification information; determining a measure of the three-dimensional position of the object in the reference frame based on said processing and decoding and based on said stored information.