Research On Robust Digital Watermarking For 3D Model

With the rapid development of 3D modeling and multimedia technology,more and more artificial 3D models and realistic 3D objects are permanently preserved in the form of digital works.However,these digital works are easy to be illegally copied and tampered in the subsequent applications,which makes information security and copyright protection of digital works face severe challenges.Digital watermarking technology of 3D model embeds the secret information into models to achieve the purpose of the copyright protection.Digital watermarking is the unique identifier for the copyright certification.Before the application and spread of 3D models,the copyright of the owner is embedded as the watermark.On the one hand,the embedded watermark does not affect the visual quality of the models.On the other hand,even models suffer from malicious attacks by the infringer,the embedded watermark can still be extracted from models so as to effectively protect the copyright of 3D models.This thesis focuses on robust 3D model watermarking algorithms.Firstly,we investigate the state-of-the-art watermarking of 3D model.Then two kinds of robust digital watermarking of 3D model are proposed on the basis of predecessors and watermarking system of 3D model is built.The main works of this thesis include:(1)To solve the problem of the robustness in 3D model watermarking,a watermarking scheme of 3D model is proposed based on improved vertex grouping and piecewise mapping function.The algorithm uses a new vertex grouping method to construct watermark embedding primitives.This grouping method makes each bin have the same number of valid vertices.Compared with the traditional grouping method,new vertex grouping method enhances the robustness of the watermark in the marginal bins.In addition,in the process of the watermark embedding,the proposed algorithm uses piecewise mapping function to reduce the distortion range of 3D model vertex,which ensures the better transparency.The proposed algorithm can completely resist common affine transformation and vertex reordering attacks.And the algorithm is remarkably robust against attacks including noise,smoothing,quantization and subdivision;(2)For the selection problem of the watermark embedding location in the 3D model watermarking,an adaptively watermarking algorithm of 3D model is proposed based on chaotic system and genetic algorithm.The algorithm uses logistic sequence and genetic algorithm to match the original watermark information and inherent information in the model.The suitable watermark embedding positions are determined by genetic algorithm.Then the algorithm adopts the adaptive watermark embedding method to adjust model vertex coordinates.Finally,initial values for logistic sequence are saved as the secret key for the watermark extraction.The experiments verify that the proposed algorithm has good transparency and can effectively resist multiple common attacks;(3)According to the above 3D watermarking algorithm,watermarking system of 3D model is built to protect the copyright.This system mainly has four modules:model loading and saving module,model interaction and visualization module,robust watermark algorithm embedding module,watermark extraction and correlation calculation module.This system can provide technical support for the copyright protection of 3D model.