<title>Deformable block motion compensation scheme for aerial video surveillance coding</title>

Abstract

We present an interpolation scheme for deformable block motion compensation based on a pseudo-perspective mapping model. The motion compensation method based on this model is targeted for coding aerial surveillance video sequences. In aerial video sequences, distortion occurs as the perspective of the surveillance camera relative to the scene changes. The traditional motion compensation method based on translational model is inadequate to compensate for this perspective distortion. One solution to overcome this problem is to use a deformable block motion compensation method with a more sophisticated model. Polynomial approximations of the perspective motion model, such as the affine and bilinear models, have been reported in the literature. Nevertheless, the affine model lacks the correct degree of freedom required to capture the effect of perspective distortion between frames. Though the bilinear model has the correct degrees of freedom, it still cannot accurately model the perspective distortion, especially near the boundaries of an image block. In this paper we propose to apply an eight-parameter pseudo-perspective mapping model for deformable block motion compensation. We developed an efficient interpolation scheme for this model based on finite element shape functions. We tested our interpolation scheme on aerial video frames in the NTSC format (720 x 480 pixels). The proposed interpolation scheme, motion-compensation algorithm, and simulation results are described. The motion compensation scheme based on the proposed mapping model yields an improvement of 1.5dB to 2.3dB in peak signal-to-noise ratio compared to a bilinear model based scheme.