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Proceedings Paper

Vertex tracking for grid-based motion compensation
Author(s): Karsten Schroeder
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Paper Abstract

To overcome some of the well-known artefacts stemming from block-based motion compensation, grid-based techniques have been proposed in the past as a promising alternative to block matching. While the latter is restricted to simple translational motion, grid-based compensation employs e.g. an affine model when triangular meshes are assumed. The theoretically superior model, however, will perform worse at object boundaries where the connectivity constraint of the meshes causes smoothing of the underlying discontinuous motion vector field. This effect can be diminished by providing an individual grid for each object in a scene. The crucial part of grid-based motion prediction is the technique of tracking mesh vertices. In contrast to block matching, motion estimation of vertices cannot be done independently without sacrificing prediction gain. This paper discuses different algorithms for vertex tracking. The issue of tracking at object boundaries and the influence of the resampling algorithm on the prediction gain are addressed in detail. Object grids, carrying both shape and motion information, are evaluated further in terms of shape coding efficiency and temporal scalability. Both aspects become important when aiming at functional coding for low bit rates, as it is currently being investigated in the framework of MPEG-4.

Paper Details

Date Published: 16 September 1996
PDF: 12 pages
Proc. SPIE 2952, Digital Compression Technologies and Systems for Video Communications, (16 September 1996); doi: 10.1117/12.251285
Show Author Affiliations
Karsten Schroeder, Univ. Dortmund (Germany)

Published in SPIE Proceedings Vol. 2952:
Digital Compression Technologies and Systems for Video Communications
Naohisa Ohta, Editor(s)

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