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Theses

Indexation de vidéos et de maillages 3D dans le contexte MPEG-7

Abstract : This thesis tackles the issue of indexing and content-based representation of multimedia data, within the MPEG-7 international standard framework.

Addressing the issue of motion-based video characterization, we first propose new similarity measures for parametric motion descriptors, based upon a family of distance functions between the associated motion fields. The issues of computational complexity optimization, spatio-temporal alignment and weighting of translational and homogeneous motion components are addressed and a mathematical procedure is proposed, implemented and objectively evaluated upon categorized synthetic and natural motion databases specifically created by the author and adopted by the MPEG-7 group for evaluating motion descriptors.

We then deal with the issue of shape-based 3D mesh model indexation and propose two different shape descriptors. Considering the geometrical and topological invariance requirements that a 3D shape descriptor should naturally satisfy, we have first defined the 3D shape spectrum, that we have proposed and promoted within the MPEG-7 standard. The 3D shape spectrum uniquely exploits the local geometrical structure of the surface, provides a very compact representation, but suffers from a high sensitivity to changes of the mesh topology. In order to overcome such a limitation, a novel shape descriptor is then proposed. Based upon the 3D Hough transform, the optimized 3D Hough descriptor is intrinsically topologically invariant. Applying a spatial alignment procedure guarantees a geometrical invariant behavior to the 3D Hough descriptor, which is then optimized in terms of compactness of representation by defining a partition of the unit sphere, invariant to changes of canonical coordinate system.

Finally, we propose a MPEG-7 compliant indexing system, integrating annotation, navigation, visualization and similarity retrieval tools and supporting several applications, such as video archiving, cliquable video and French sign language indexing and recognition. The system demonstrates for the first time the effectiveness of MPEG-7 generic description schemes within the framework of the above-mentioned applications.
Keywords : Indexation 3D MPEG-7
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Theses
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https://tel.archives-ouvertes.fr/tel-00273222
Contributor : Francoise Preteux <>
Submitted on : Monday, April 14, 2008 - 5:05:46 PM
Last modification on : Friday, October 23, 2020 - 4:39:38 PM
Long-term archiving on: : Thursday, May 20, 2010 - 9:04:44 PM

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  • HAL Id : tel-00273222, version 1

Citation

Titus Zaharia. Indexation de vidéos et de maillages 3D dans le contexte MPEG-7. Informatique [cs]. Université René Descartes - Paris V, 2001. Français. ⟨tel-00273222⟩

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