Determination of affine transforms from object contours with no point correspondence information

A method for determination of the affine transform relating projections of planar contour features is developed and tested experimentally. The method does not require knowledge of any point correspondences and is applicable to general affine transforms including those resulting from rotations of contours out of the plane of projection. This algorithm, together with a feature extraction procedure to derive contours (open or closed loops) from images of the complete object could form the basis of a system for determination of orientation and identity of a wide class of objects from 2-D views. The technique is based on the relation of moment tensors derived from two views of the planar contours, and determines the affine transform by solution of a set of linear equations.