Patent ID: 6980229

Claim:
A system for tracking a movable structure, comprising: at least one actively emissive fiducial; at least one video camera; wherein either the camera or the fiducial is mounted on the movable structure, so that the camera can capture an image of the fiducial as the structure moves; means for capturing the image from the video camera; means for determining the location of the fiducial in the captured image, comprising means for resolving the energy received from the active fiducial separately in a plurality of separate areas of a captured video frame, means for comparing the resolved energy to a predetermined energy threshold to find areas with energies above the threshold, and means for resolving the centroid of a larger area of the captured video frame comprised of a separate area with an energy above the threshold and a plurality of contiguous separate areas; and means, responsive to the means for determining, for resolving the heading of the movable structure.