A real-time model-based method for 3-D object orientation estimation in outdoor scenes

This letter presents a new method for real-time determination of the three-dimensional (3-D) orientation, i.e., the rotation angle with respect to one of the principal object axes, of a moving known object from a monocular image sequence, The method is composed by three steps: 1) extraction of the morphological skeleton from binary images, 2) projection of the skeleton function on two planes and its analytical approximation by nonuniform rational B-splines, and 3) comparison with a set of data stored into a model. database, Several experiments per-formed on real images prove the method's validity.