A New Geometric Constrained Structure and Its Projective Invariant

Geometric invariant is an effective tool in recognizing 3D object from a single gray image. However, researches show that only some special geometric constrained structures possess projective invariants. Therefore, it is necessary to study and find out more such structures. A new geometric constrained structure with three planes and five lines and its projective invariant are proposed. This structure is simpler than the (Sugimoto's) structure of six lines on three planes. So, more projective invariants can be extracted from the same object, which can improve the stableness of recognition. At the same time, because the new structure widely exists in the artificial polyhedral objects and buildings, it is more suitable for the recognition of such kinds of objects. The experimental results show that the proposed structure has projective invariant which does not change with the variation of the viewpoints.