Segmentation au sens du mouvement de maillages dynamiques

Cet article décrit une nouvelle méthode de segmentation au sens du mouvement de maillages 3D dynamiques. L'approche repose sur un principe de décimation hiérarchique sous contrainte d'erreur quadratique moyenne de compensation de mouvement. La segmentation obtenue est exploitée dans l'étape de compensation de mouvement par le codeur d'animation 3D FAMC (Frame-based Animated Mesh Compression) développé par les auteurs et récemment promu (Janvier 2007) dans le standard MPEG-4 en tant qu'amendement 2 de la partie 16 - AFX (Animation Framework eXtension). Les résultats expérimentaux montrent des gains en débits significatifs (de 20% à 80%) de l'approche FAMC par rapport aux techniques de l'état de l'art

TFAN a low complexity 3D Mesh Compression algorithm

This paper proposes a novel approach for mono-resolution 3D mesh compression, called TFAN (Triangle Fan-based compression). TFAN treats in a unified manner meshes of arbitrary topologies, i.e., manifold or not, oriented or not, while offering a linear computational complexity (with respect to the number of mesh vertices) for both encoding and decoding algorithms. In addition, the TFAN compressed representation is optimized for real-time decoding applications. In order to validate the proposed approach, two databases have been considered for experimentations. The first is the MPEG-4 test set, which includes over 3500 general purpose manifold meshes. The second, related to the French national project SEMANTIC-3D, includes over 4000 computer assisted design (CAD) meshes of highly irregular, non-manifold topologies. In both cases, the TFAN approach outperforms existing techniques such as MPEG-4/3DMC (3D Mesh Coding) or Touma and Gotsman, with decoding times lower by an order of magnitude at equivalent or even better levels of compression efficiency (W10% in bitrate). In addition, when applied to non-manifold 3D data, the compression performances are significantly enhanced (6-30% gain in bitrate). Due to its high compression performances the TFAN approach has been recently retained for ISO standardization, within the framework of the MPEG-4/AFX standard

A DCT-based approach for dynamic 3D mesh compression,”

Abstract This paper proposes a novel approach for 3D mesh compression, based on a skinning animation technique. The core of the proposed method is a piecewise affine predictor coupled with a skinning model and a DCT representation of the residuals errors. The experimental evaluation shows that the proposed skinning-based encoder outperforms (with bitrates gains from 47% to 67%) GV, RT, MPEG-4/AFX-IC, D3DMC, PCA and Dynapack techniques

A preliminary evaluation of 3D mesh animation coding techniques

This paper provides an overview of the state-of-the-art techniques recently developed within the emerging field of dynamic mesh compression. Static encoders, wavelet-based schemes, PCA-based approaches, differential temporal and spatio-temporal predictive techniques, and clustering-based representations are considered, presented, analyzed, and objectively compared in terms of compression efficiency, algorithmic and computational aspects and offered functionalities (such as progressive transmission, scalable rendering, computational and algorithmic aspects, field of applicability...). The proposed comparative study reveals that: (1) clustering-based approaches offer the best compromise between compression performances and computational complexity; (2) PCA-based representations are highly efficient on long animated sequences (i.e. with number of mesh vertices much smaller than the number of frames) at the price of prohibitive computational complexity of the encoding process; (3) Spatio-temporal Dynapack predictors provides simple yet effective predictive schemes that outperforms simple predictors such as those considered within the interpolator compression node adopted by the MPEG-4 within the AFX standard; (4) Wavelet-based approaches, which provide the best compression performances for static meshes show here again good results, with the additional advantage of a fully progressive representation, but suffer from an applicability limited to large meshes with at least several thousands of vertices per connected component. 1

3D Mesh Coding Techniques Applied to CAD Data: A Comparative Evaluation

This paper presents a study of 3D mesh compression techniques within the specific framework of CAD applications. A state-of-the art of 3D mesh compression approaches is first presented and analyzed under the light of CAD data specificities. A CAD corpus, provided by the French car manufacturer RENAULT is then quantitatively analyzed in terms of geometricotopological properties. This analysis reveals that CAD content often violates the common regularity assumptions underlying 3D coding approaches. Finally, a comparative evaluation of several state-ofthe art techniques is presented. Experimental results show the difficulties of general purpose coders to efficiently handle CAD data, which confirms the need of designing CAD-specific coding techniques