Research On Robust Watermarking For 3D Models

The multimedia information security problems including copyright piracy emerged as side effects over network. 3D mesh models are being used widely as a new type of media, and the problems of copyright protection and content authentication have become the hotspots of 3D mesh processing. Meanwhile, with the rapid growth of the data volume of 3D mesh models, it becomes necessary to process 3D data in the compressed domain. In this dissertation, we study the technologies of 3D model watermarking and compression. The main contributions of this dissertation are:Firstly, state of art watermarking technologies for 3D mesh models, especially those of reversible watermarking, and some typical techniques are systematically introduced here; we also briefed the basic concepts, research background, significance and state of art technologies of 3D mesh models compression, including some developments of watermarking techniques in the compressed domain. The above summarizations are aimed to provide new thoughts in the areas of watermarking, compression and their combination.Secondly, a robust watermarking scheme for 3D mesh models is proposed: we select vertices'coordinates as primitives for embedding watermark. By introducing the parallelogram impedance property here, we make the watermark embedding intensity adaptive to the local geometry characteristic of the vertex. At the same time, the direction along which the watermark bit is embedded is also adaptive to the local geometry, which is rather a novel idea. The proposed adaptive watermarking scheme enables more energy of watermark to be embedded with imperceptibility, so the stego mesh can be resilient to higher intensity of attacks than with traditional schemes. The experiment results show that the watermark embedded is rather robust to various attacks such as adding noise, rotation, translation, scaling, insecting, down-sampling and some of their combinations. Also the computation complexity is rather low.Thirdly, we proposed two algorithms for 3D mesh models compression using vector quantization: one scheme is based on an extended codebook, with which the correlations between indices of adjacent vertices are adopted and...