Research On Digital Watermarking Technology Based On 3D Model Grid Structure

At present,digital watermarking is more and more widely applicated,especially in the Internet era,the issue of copyright protection has also attracted more and more attention.With the development of 3D modeling technology,3D model can also be used in digital watermarking technology.As the transmission carrier,3D model has the characteristics of large embedding capacity and good visual effect,so the research on 3D model word watermarking has become a hot spot in the field of information hiding.At present,the research on 3D model digital watermarking is mainly based on a single embedded region.The performance of the algorithm will be limited.At the same time,the robustness of the algorithm is not strong.This thesis mainly studies the digital watermarking technology of three-dimensional model grid structure,mainly studies the representation method of three-dimensional model,the characteristics of grid model,three-dimensional model digital watermarking system,attack type,algorithm evaluation standard and technical difficulties.On the basis of the above research,two digital watermarking algorithms based on three-dimensional mesh structure are proposed:(1)a dual digital watermarking scheme based on mesh regularity of three-dimensional mesh model.The algorithm uses double embedding.Firstly,it calculates the regularity of the triangular mesh surface of the model,and modifies the order of the obj file surface of the 3D model after classification according to the regularity to complete the watermark embedding.Secondly,it filters the triangular mesh according to the regularity,calculates the angle between the two adjacent triangular mesh plane normals,and uses discrete cosine transform to process the angle sequence,embeds the watermark into the transformation coefficient,and then reverses the discretization the 3D model with watermark is obtained by cosine transform.(2)A digital watermarking scheme based on the mesh characteristics of 3D model.The algorithm first calculates the vertex strength of each vertex of the model,and constructs a two-dimensional matrix by dividing the three-dimensional model into blocks.The watermark information is embedded in the matrix by using singular value decomposition method to complete the watermark embedding in the transform domain.The watermark embedding in the spatial domain is completed by calculating the mesh strength and modifying the storage order of the model according to the embedding rules.In this paper,the performance of the proposed watermarking scheme is analyzed and simulated.In the experiment of dual digital watermarking algorithm based on three-dimensional model mesh regularity,the experimental results show that the maximum root mean square error of the proposed algorithm is 27.81%,54.58% and 80.60% lower than that of the contrast algorithm,respectively,which indicates that the algorithm is invisible,and the performance of the proposed algorithm is better than that of the contrast algorithm in resisting mesh simplification,model clipping and noise attacks;in joint attacks,the proposed algorithm is more effective than the contrast algorithm In the experiment,the average correlation coefficient and bit error rate are 0.516 and 46.50% when dealing with 25%clipping,1% noise amplitude and 20% simplification attacks at the same time,and the bit accuracy rate can reach 52.50% when resisting the high-intensity joint attacks of 36%clipping,40% simplification and 2% noise amplitude.In the experiment of digital watermarking scheme based on three-dimensional model mesh and vertex structure,the experimental results show that the signal-to-noise ratio and mean Hausdorff distance of the proposed algorithm are 7.91% and 9.79% higher and 10.48% and 23.11% lower than those of the contrast algorithm,respectively.In random noise,compression attack and model cutting attack,the performance of the proposed algorithm is also better than that of the comparison algorithm in varying degrees.The digital watermarking scheme of 3D model grid structure proposed in this paper can help solve the problems of 3D model multimedia copyright protection and content security authentication.