Research On Digital Watermarking Algorithm For 3D Mesh Model

The 3D model of modern industrial products plays an important role in computer-aided design and engineering.The copyright protection of 3D model is of great significance.Digital watermarking is widely used in copyright protection.Copyright is protected by embedding watermark information into the original carrier.3D model not only contains data information,but also topological structure.The representation of 3D model is not unique.The difficulty and depth of the 3D model digital watermarking are greatly increased due to the complexity of the 3D model representation and the diversity of attacks.From the aspects of copyright protection,content authentication and watermarking capacity improvement,this study summarizes and analyzes the existing 3D model digital watermarking algorithms and proposes improved schemes.The main work includes the following two aspects:First,aiming at the low watermarking capacity in the existing algorithms,a digital watermarking algorithm based on integer optimization for high capacity 3D mesh model is proposed.The 3D model lacks the parameterization standard and cannot directly modify its frequency domain coefficients to embed the watermark,the robustness of the algorithm is limited.This study embeds the original watermark information into the discrete Fourier transform domain coefficients of the carrier image.It uses addition invariance to add the watermark information to the vertex data of the 3D model,and improves the robustness of the watermark;The 3D mesh model is transformed by the spherical coordinates,the distances between the coordinate components are sorted.The sparse vertices are selected as the embedding vertices;The optimal embedding positions of the vertices are screened by the integer optimization strategy to embed watermark,and reduce the influence of the embedding of the watermark on the ordering of the coordinate components.The integer optimization strategy is to embed watermarked 3D model to minimize disturbance.The algorithm supports high capacity watermark embedding.It has good transparency,and has good robustness to vertex reordering,panning,scaling and noise attacks.Second,in order to realize copyright protection and content authentication,a 3D watermarking algorithm based on grouping strategy and neighborhood relational positioning is proposed.The algorithm achieves the copyright protection and content authentication of the 3D model by embedding the robust watermark and the fragile watermark.In case of robust watermark,watermark embedded by grouping vertices and using the distribution of vertices in 3D model.In case of fragile watermark,watermark embedded watermarking by adjusting the geometric relationship between the model vertices and a neighborhood of circles.The dual-objective optimization model is used to solve the problem of the mutual interference between the robust watermark and the fragile watermark.The experiment results show that the robust watermark and the fragile watermark in the algorithm do not interfere with each other,and the robust watermark can resist common attacks such as noise and simplification.The fragile watermark has tamper localization function.