Simplification Resilient LDPC-Coded Sparse-QIM Watermarking for 3D-Meshes

We propose a blind watermarking scheme for 3-D meshes which combines sparse quantization index modulation (QIM) with deletion correction codes. The QIM operates on the vertices in rough concave regions of the surface thus ensuring impeccability, while the deletion correction code recovers the data hidden in the vertices which is removed by mesh optimization and/or simplification. The proposed scheme offers two orders of magnitude better performance in terms of recovered watermark bit error rate compared to the existing schemes of similar payloads and fidelity constraints.Comment: Submitted, revised and Copyright transfered to IEEE Transactions on Multimedia, October 9th 201

A RUNLENGTH CODED ADAPTIVE QIM FOR THE CULTURAL HERITAGE 3D MODELS AUTHENTICATION

We describe a simple and effective quantization scheme for a digital 3D cultural heritage models authentication and watermarking. It is based on runlength coding which converts a class of deletion channels that have infinite memory into memoryless channels. We consider a novel application of this technique in multimedia watermarking and authentication using quantization index modulation operating on the three dimensional mesh vertices, which are invariant to geometric and topological transformation. Vector of the vertex indices is extracted from a huge digital 3D model using our powerful vertex extraction tool. The coding recovers the data hidden in the vertices removed by the process of mesh simplification

DIGITAL SECURITY: 3D GEOMETRY PROTECTION OF THE AUTOMATICALLY RESTITUTED HISTORICAL BUILDINGS

This paper describes a novel method of data protection of the three-dimensional (3D) models that are obtained from automatic process of geometric restitution, using old two-dimensional (2D) architectural and artistic drawings. The first contribution of our research is the algorithm that includes several image processing steps, which are required in order to define walls, staircases and openings from the digitalized hand drawn architectural plans. The result of this step is detailed 3D model of the digitally processed historical building plans. The experimental confirmation of the algorithm accuracy is 3D model of the Chateau de Versailles, which is descripted by old hand drawings, dating between the end of the XVII and the XIX century. Next part of our research is theoretical and mathematical analysis of geometrical features of such 3D model that is a result of the image processing algorithm. The key-achievement of this part is new method of protecting the geometrical data using optimized adaptive Sparse Quantization Index Modulation (QIM) for embedding data bits into essential structure of the generated model. As a final result we present a secure authentication of the automatically restituted 3D model of the historically important artifact

INFLUENCE OF LOCAL CURVATURE ESTIMATION ON THE 3D MESH TOPOLOGICAL AND GEOMETRIC STABILITY

The influence of curvature estimation on the 3D mesh topological and geometric stability is considered in this paper. It can be shown that, in the case of the most commonly used methods for local curvature estimation, the nontrivial calculus of curvature can lead to mistakes and treat as noise holders of shape. Therefore, new algorithms for solving problems in every step of these processes are proposed. The proposed algorithms are simple and quick from the viewpoint of the mathematical calculations, because they assume only a few extra steps in the algorithm of curvature evaluation. Besides, the new approach provides more accurate results then other approaches, and also reduces the possibility of 3D mesh geometry damages

A Method for Determining the Shape Similarity of Complex Three-Dimensional Structures to Aid Decay Restoration and Digitization Error Correction

none5noThis paper introduces a new method for determining the shape similarity of complex three-dimensional (3D) mesh structures based on extracting a vector of important vertices, ordered according to a matrix of their most important geometrical and topological features. The correlation of ordered matrix vectors is combined with perceptual definition of salient regions in order to aid detection, distinguishing, measurement and restoration of real degradation and digitization errors. The case study is the digital 3D structure of the Camino Degli Angeli, in the Urbino’s Ducal Palace, acquired by the structure from motion (SfM) technique. In order to obtain an accurate, featured representation of the matching shape, the strong mesh processing computations are performed over the mesh surface while preserving real shape and geometric structure. In addition to perceptually based feature ranking, the new theoretical approach for ranking the evaluation criteria by employing neural networks (NNs) has been proposed to reduce the probability of deleting shape points, subject to optimization. Numerical analysis and simulations in combination with the developed virtual reality (VR) application serve as an assurance to restoration specialists providing visual and feature-based comparison of damaged parts with correct similar examples. The procedure also distinguishes mesh irregularities resulting from the photogrammetry process.openVasic I.; Quattrini R.; Pierdicca R.; Frontoni E.; Vasic B.Vasic, I.; Quattrini, R.; Pierdicca, R.; Frontoni, E.; Vasic, B

Nouvelles méthodes de synchronisation de nuages de points 3D pour l'insertion de données cachées

This thesis addresses issues relating to the protection of 3D object meshes. For instance, these objects can be created using CAD tool developed by the company STRATEGIES. In an industrial context, 3D meshes creators need to have tools in order to verify meshes integrity, or check permission for 3D printing for example.In this context we study data hiding on 3D meshes. This approach allows us to insert information in a secure and imperceptible way in a mesh. This may be an identifier, a meta-information or a third-party content, for instance, in order to transmit secretly a texture. Data hiding can address these problems by adjusting the trade-off between capacity, imperceptibility and robustness. Generally, data hiding methods consist of two stages, the synchronization and the embedding. The synchronization stage consists of finding and ordering available components for insertion. One of the main challenges is to propose an effective synchronization method that defines an order on mesh components. In our work, we propose to use mesh vertices, specifically their geometric representation in space, as basic components for synchronization and embedding. We present three new synchronisation methods based on the construction of a Hamiltonian path in a vertex cloud. Two of these methods jointly perform the synchronization stage and the embedding stage. This is possible thanks to two new high-capacity embedding methods (from 3 to 24 bits per vertex) that rely on coordinates quantization. In this work we also highlight the constraints of this kind of synchronization. We analyze the different approaches proposed with several experimental studies. Our work is assessed on various criteria including the capacity and imperceptibility of the embedding method. We also pay attention to security aspects of the proposed methods.Cette thèse aborde les problèmes liés à la protection de maillages d'objets 3D. Ces objets peuvent, par exemple, être créés à l'aide d'outil de CAD développés par la société STRATEGIES. Dans un cadre industriel, les créateurs de maillages 3D ont besoin de disposer d'outils leur permettant de vérifier l'intégrité des maillages, ou de vérifier des autorisations pour l'impression 3D par exemple. Dans ce contexte nous étudions l'insertion de données cachées dans des maillages 3D. Cette approche permet d'insérer de façon imperceptible et sécurisée de l'information dans un maillage. Il peut s'agir d'un identifiant, de méta-informations ou d'un contenu tiers, par exemple, pour transmettre de façon secrète une texture. L'insertion de données cachées permet de répondre à ces problèmes en jouant sur le compromis entre la capacité, l'imperceptibilité et la robustesse. Généralement, les méthodes d'insertion de données cachées se composent de deux phases, la synchronisation et l'insertion. La synchronisation consiste à trouver et ordonner les éléments disponibles pour l'insertion. L'un des principaux challenges est de proposer une méthode de synchronisation 3D efficace qui définit un ordre sur les composants des maillages. Dans nos travaux, nous proposons d'utiliser les sommets du maillage, plus précisément leur représentation géométrique dans l'espace comme composants de base pour la synchronisation et l'insertion. Nous présentons donc trois nouvelles méthodes de synchronisation de la géométrie des maillages basées sur la construction d'un chemin hamiltonien dans un nuage de sommets. Deux de ces méthodes permettent de manière conjointe de synchroniser les sommets et de cacher un message. Cela est possible grâce à deux nouvelles méthodes d'insertion haute capacité (de 3 à 24 bits par sommet) qui s'appuient sur la quantification des coordonnées. Dans ces travaux nous mettons également en évidence les contraintes propres à ce type de synchronisation. Nous discutons des différentes approches proposées dans plusieurs études expérimentales. Nos travaux sont évalués sur différents critères dont la capacité et l'imperceptibilité de la méthode d'insertion. Nous portons également notre attention aux aspects sécurité des méthodes