Form Recognition Using Moment Invariants for Three Dimensional Perspective Transformations

The invariant recognition of forms is important for many tasks. The purpose of this paper is to consider algebraic and moment invariants for perspective transformations. These are important because every lens system induces a perspective transformation. The approach consists of considering the non-linear perspective transformation in a higher dimensional, homogenous space. In homogeneous space the perspective transformation is linear and algebraic invariant theory may be used to determine absolute algebraic and moment invariants. The cross ratio is a well known perspective invariant. New moment invariants corresponding to the perspective transformation are derived. Examples are presented to demonstrate the theoretical approach. The significance of this work lies in the importance of invariant recognition for both human and machine vision.