Design Of Robust Watermarking Algorithms And A Demo System For3D Mesh

In the last decade, digital watermarking has emerged as an important approach toproviding copyright protection and ownership assertion closely related to the area ofsteganography. Most digital watermarking techniques have focused mainly on classicalmedia data types like audio, images, and video because of the widespread deploymentof these media online. Recently there is increased interest in watermarking of3-Dobjects due to the ever-increasing diffusion of such objects in many areas such asarchitecture design, virtual reality, entertainment, mechanical engineering and culturalheritage. Watermarking of3-D objects however has not reached the same level ofmaturity as that of still images and video.This work make efforts in programming to realize3D mesh render and process,designing a watermarking demo system and designing a new watermarking scheme. Thefirst level of the3D mesh render and process demo system comprises of opening3Dmesh data files, rendering and showing mesh, alternative render mode, geometrictransformation, simplifying mesh and saving mesh file.We give a thorough review of the relevant literature about affine transformationbased space domain watermarking. We commence by introducing the conception ofdepth-searching reference plane and basis face. Then, we explore the use of the distanceratio into watermark sequence to enhance the robustness of the affine transformation, asthe distance ratio is affine invariant. A demo is used to stimulate for this.Since the less robustness of above space domain watermarking, to overcome thisproblem, in this work, we draw on recent work on classic image watermarking line andthen propose a more robust watermarking scheme based on discrete norm biorthogonalnon-uniform B-spline wavelets (called BWDN-based watermarking). There are six stepsto our BWDN-based watermarking, namely a) transforming the spherical coordinates, b)grouping vertices, c) ordering vertices, d) determining knot vector, e) non-uniformB-spline wavelet transformation, f) lower-resolution coefficients using watermarkembedding. The work is organized as follows. Firstly, we give a thorough review of thetheory and methods for3D mesh signal processing (i.e. the mesh subdivision, signal process based on vertex relaxation operator, geometry image, digital geometry process,3D polygons multi-resolution wavelet decomposition and non-uniform B-splinewavelet). Then we examine the performance of our BWDN-based watermarkingalgorithm by importing the BWDN software kit into the second level of the demosystem. Experimental results demonstrate the effectiveness of our proposed method. Incontrast to most existing watermarking methods, it can achieve higher robust againstadding, mesh simplifying, mesh cropping, vertices reordering and similaritytransformation.The non-blind BWDN-based watermarking decreases the security of thewatermarking systems, because security requires that the cover media should not beavailable in the watermark detection procedure. For making progress, a novelwatermarking scheme is proposed in this work. In the proposed algorithm, a3D meshmodel is partitioned into patches using feature vertexes from the roughness measure,then each patch is mapped into a plane along the normal direction of feature vertex andso a range image is generated. Each image is represented as a group of quasi-uniformB-spline curves and these curves are performed wavelet decomposition. The watermarkbits are embedded into the low-resolution parts and a inverse mapping process isexecuted to obtain a watermarked model. The watermark can be extracted based onfeature vertexes’ coordinates and original range images. The watermarking is verified tobe robust against mesh simplification, cropping, vertex randomization, noise adding,re-sampling and similarity transform.