Browsing by Author "Eshraghi Boroojeni, Mahsa"
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Item Open Access 3D mesh watermarking(2008) Eshraghi Boroojeni, Mahsa; Samavati, Faramarz F.3D watermarking methods embed a hidden watermark into 3D models for the main purpose of copyright protection and content authentication. The growing use of 3D models in various fields of industry, such as games, animation, virtual reality, and cultural heritage, along with the possibility of easy reproduction and distribution, has drawn the attention to copyright protection of 3D models. This thesis develops a watermarking framework for polygonal meshes that attains robustness against a list of accessible attacks. A watermark is embedded into the geometry of a mesh by perturbing the mesh vertices along t heir tangent space to achieve invisibility. The mesh capacity for the embedded watermark can be as high as the number of its vertices, which is usually a fairly large number. To sort out the issue of robustness, a list of the most accessible attacks through common graphics tools is proposed that includes affine transformations, geometrical deformations, topological attacks, subdivision attacks, vertex reordering, and combination of these attacks. To achieve robustness against the proposed list of attacks, a set of attack recovery techniques are developed. Geometric segmentation is proposed to recover the inserted watermark against geometrical deformations and topological attacks. Geometric indexing is performed to resist vertex reordering attacks. Robustness against affine transformations is achieved through a coordinate normalization scheme. Finally, a resolution normalization scheme is proposed to resist the subdivision attacks.