Digital Watermarking For3D Model Based On Geometric Characteristic

With the wide application of digital multimedia technology on the internet, it is moreand more interested for people in digital products because of its convenient and rapid. Itis developed more and more quickly about electronic publishing, network video, digitallibrary and e-commerce. It not only brought convenience to people but also broughthidden danger of security. It is become more and more easily about illegal copying andtampering. So this let people pay attention to copyright protection,content authenticationand information security. Digital watermarking arises at the historic moment.2D digitalwatermarking used in image, video, audio has become ripe. Accompanied by the rapiddevelopment of graphic arts,3D games, animation and virtual reality,3D digitalwatermark need to be addressed. This paper mainly studies the3D model watermarkingbased on geometric features. The main research content of this paper is as follows:First, it is introduced about classification and characteristics of digital watermarking.Then it is introduced about domestic and foreign research background and significance.It is introduced about the contents and significance of digital watermarking for thethree-dimensional model, then the main content and structure of the paper will beintroduced.Second, it is introduced about the basic theory of digital watermarking forthree-dimensional models. The process of embed and extract about digital watermarkingfor three-dimensional will be introduced, which let us understand how to embed awatermark and how the watermark is detected, and then the characteristics of digitalwatermarking for three-dimensional models, the classification of algorithm, the means ofattack, and the solution to attack also will be illustrated. Then the evaluation standard ofdigital watermarking for three-dimensional models is put forward. The representingmethod and the topological structure of three-dimensional models also are proposed.Finally, The algorithm of digital watermarking for three-dimensional models is analysedand understood in depth.Third, digital watermarking for3D mesh model based on roughness is proposed.Candidate vertex is selected by the angel between the normal vector and its weightedaverage. The normal vector which is belong mass point about the related space of a localgeometric space. The roughness of the model is used to choose embed vertex. First of all,the center of the minimum bounding box is used to as the center of the three-dimensionalmodel. We can make use of the geometric characteristics about the point-to-center distance to divide block. According to the roughness to obtain the right value. Theroughness is obtained by the mean of the angle, which is the normal vector of vertex ’sadjacent area. Another roughness is obtained by the ratio of the mean about area, whichis adjacent triangle of vertex and all triangles. Weights are compared to choice the embedvertex. Experiments show that this algorithm not only guarantee robustness, but alsoenhance the imperceptibility of3D model digital watermarking. This algorithm is moresuitable for copyright protection for three-dimensional model.Fourth, digital watermarking for3D model based on geometric characteristic isproposed, which improve the robustness of the double watermarking forthree-dimensional models. We should convert a3D model into a geometric invariantspace. Watermarking is embedded by change vertex and topological information becauseof that they are independent and uncorrelated. The watermarking in the first layer isembedded by comparison between the length of feature point and the weighted averagelength. The weighted average length is between feature point and its adjacent point. Thewatermarking in the second layer is embedded by the affine invariant norm. The vertexsequence of triangle is changed by the maximum and minimum of the affine invariantnorm. The simulation results show that which not only enhance the robustness, but alsowithstand such as translation, rotation, scaling, shearing, noise attack.Fifth, watermarking algorithm for3D model was applied on the3D model of thekey role about three dimensional animation. The imperceptibility of the3D model of thekey role about three dimensional animation is enhanced by the algorithm of digitalwatermarking for3D model based on roughness, which ensure the requirements of the hdfor people. The robustness of the3D model of the key role about three dimensionalanimation is improved by digital watermarking for3D model based on geometriccharacteristic. Watermark information which is detected can be used as a legal basis toprove the brand, the ownership of copyright. In the process of transmission, afterattacked, a layer of the watermark is damaged, there is another layer to ensure the safetyof the transmission.