Shape estimation of articulated 3D objects for object-based analysis-synthesis coding (OBASC)

摘要

This paper investigates shape estimation of articulated 3D objects for object-based analysis-synthesis coding based on the source model of ‘moving articulated 3D objects’. For shape estimation three steps are applied: shape-initialization, object-articulation and shape-adaptation. Here, a new algorithm for object-articulation is introduced. Object-articulation subdivides a rigid model object represented by a mesh of triangles into flexibly connected model object-components. For object articulation, neighboring triangles which exhibit similar 3D motion during the image sequence are clustered into patches. These patches are considered to be the model object-components. For 3D motion estimation of a single triangle, a more reliable algorithm is proposed. The reliability is measured by the probability of convergency to correct parameters. For improving the reliability both, a more robust technique is applied and the triangle and its neighborhood are evaluated by the estimation algorithm. For clustering, a frame to frame clustering method which considers clustering results obtained in previous frames is presented. The developed algorithm for object-articulation is incorporated in OBASC. Typical videophone test sequences were applied. Compared to OBASC based on the source model of ‘moving rigid 3D objects’, the transmission rate decreases from 63.5 to 53 kbit/s at a fixed image quality measured by SNR. Furthermore, a realistic object articulation of a model object ‘body’ into object-components ‘head’ and ‘shoulders’ can be achieved without a priori knowledge about the scene content.