MORSE is an object recognition system, based on geometric invariants of 3D structures taken from a single 2D intensity view. The system exploits the geometric constraints inherent in object classes such as polyhedra, rotational symmetry, bi-lateral symmetry and extruded surfaces. Invariants have been used in the past to index many of these classes, but MORSE is designed to treat multi-class recognition in a uniform system architecture. The class constraints are also used to drive image feature extraction and grouping.