Sub pixel accuracy of fiducial marks using least square estimator
David J. Coumou · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2005
An image processing architecture has been developed that executes a concatenated algorithm to determine the presence of multiple fiducial marks on an image plane, locates the estimated position of the fiducial marks in the image, calculates subpixel accuracy of the fiducial mark, and translates the x and y coordinates of the fiducial marks to absolute distance and phase relationships between fiducial marks. The fiducial mark is an object with an outer circular boundary and two inner lines that intersect to provide an object with symmetry. This symmetry is crucial for the requirements of rotation and scaling invariant, specifically for the process of identifying the presence of the fiducial mark in the image plane. Video is used for imagery of the fiducial marks.