Three-dimensional Geometric Model Of Digital Watermarking Technology And Algorithms

Digitized multimedia data facilitate the processing, distribution and storage of multimedia information, enhance the efficiency and accuracy of information presentation. But the undesirable side effects are obvious: the unauthorized redistribution of the copyrighted multimedia data without loss of fidelity. Intellectual property protection is one of the most pressing concerns for content creators and owners who distribute and deliver their content in the Information Era. Digital watermarking, which originates from steganography, provides a novel way for the protection of intellectual property rights, and becomes a hot spot in the research field of multimedia data security in recent years. Current watermarking technology focuses on media types like still images, and video and audio streams. In contrast, the problem of watermarking 3D models has received less attention from researchers. But, more and more CAD-based 3D data is entering the World Wide Web. Accordingly, companies or copyright owners who present or sell their products in virtual space will face copyright-related problems. The straightforward demand is to prevent their 3D-based material from unauthorized use. As a new way for the protection of information copyright, digital watermarking will possess extensive application perspective in this area. In Chapter 1, we first describe the basic concepts of Steganography and digital watermarking, and introduce some basic concepts of digital image watennarking. Then we expound the definition, background, classification and requirements about digital watermarking of 3D models. We propose a general framework of digital watermarking system of 3D models. Then, we analyze the state of art of digital watermarking algorithms of 3D models. Following this, we give a discussion about the robustness of watermarks, i.e., attack analysis. We still discuss some possible research directions. We also briefly introduce some programming environments and software toolkits involved in our thesis. Finally, we outline the thesis. In Chapter 2, we present the idea of mesh watermarking based on digital geometry processing (DGP). We first introduce the background of DGP and some related work. By constructing planar parameterization for arbitrary meshes, all kinds of image frequency-domain watermarking algorithms can be applied to 3D models. The algorithms described in the following chapters are all based on this parameterization algorithm. In Chapter 3, we first introduce the background and related work of DCr-based digital watermarking algorithms. Then we apply the image D(T-based watermarking algorithms, which had been presented by Cox, Piva and Fotopoulos, to 3D models. Experimental results and attack analysis show that these algorithms are transparent, robust, accurate and cost-efficient. In Chapter 4, we first introduce the background and related work about DWT-based digital watermarking technology. Then we apply the image DWT-based watermarking algorithms, which had been presented by Wang and Xia, to 3D models. Experimental results and attack analysis are given. In Chapter 5, we conclude the thesis, together with some possible research directions in the future.