A two-step pose estimation method based on four non-coplanar points

The existing approaches to a solution of object pose fall into two distinct categories: analytical solutions and iterative solutions. In this paper, a two-step pose estimation method based on four non-coplanar points is studied by combining the advantages of the above two methods. In the first step, the scaled orthographic projection model is used to approximate the perspective projection model to construct the analytical solving model of points coordinates in the camera coordinate system. In the second step, an iterative method based on the geometrical constraints formed by the points is introduced, and the points coordinates obtained in the first step are passed to the current step being used as initial values of the iterative process. The proposed method is then compared with two other existing methods. Experimental results demonstrate that the proposed method has the advantage of lower computational cost. The accuracy, which is the main concerns during the real-time applications, is also improved.