Research On Watermarking Of Dynamic Mesh Sequence

With the rapid development of computer graphics technology and Internet,the application and dissemination of 3D model and dynamic geometric model are becoming more and more convenient.Meanwhile,the illegal dissemination of 3D model has attracted people's attention.Because the acquisition of 3D model requires a lot of manpower and material resources,the problem of copyright protection of 3D model needs to be solved urgently.In this paper,we focus on the research of the watermarking algorithm of 3D mesh sequences,which is an important research combining of the computer graphics and intellectual property.Compared with the research of 3D static mesh,the research of 3D dynamic mesh sequence watermarking starts relatively late and the related work is not much,which makes the research of this paper has a lot of theoretical significance.This paper proposed three kinds of watermarking strategies according to the dimension of the protection of the mesh sequence.They are respectively intra frame watermarking algorithm,inter frame watermarking algorithm and intra-inter frame watermarking algorithm.Then,two kinds of watermarking algorithms are proposed in this paper.The one is an intra algorithm which is based on the STED error minimization.The other is an inter algorithm which is based on local energy and motion characteristics.The process of the first algorithm is as follow.First,calculates the vertex norm of each mesh model.Then,according to a certain latitude interval,mesh is divided into different regions.The average vertex norm of each region is calculated to form a mean matrix.Next,cuts the mean matrix of vertex norm into small sub-matrix according to the size of watermarking.The maximum singular value of each sub-matrix is quantified.Finally the sequence reconstruction is achieved by minimizing the STED error.The second algorithm first cuts the mesh sequence into rigid area using rigid segmentation.Then the rigid block is divided into as many as possible non overlapping matrix blocks.Modifies the DCT intermediate frequency coefficients of each matrix to embed watermarking.Finally,the proposed algorithms are evaluated from two aspects which are transparency and robustness.Compared to two existing watermarking algorithms,our methods have good performance on both transparency and robustness,which means they not only can resist static mesh attacks such as affine transformation,noise,smooth,but also can resist the dynamic mesh sequence attacks such as frame deletion,frame averaging,and frame switching.