Research On Digital Watermarking Algorithm Of NURBS Models Based On Non-Uniform B-Spline Wavelets

The digital watermarking technique is more and more studied as a method in copyright protection and internet information safety.In recent years,more and more scholars do the related research in this technique.With the development of the advanced manufacturing technology and the virtual realistic technology and the widely applying of the CAD,CAM and CAE,Geometry-based 3D models are more and more appearing in the internet.As a useful technique of digital products,the problem of the copyright protection is being one of the research interest in the field of watermarking research.This dissertation first introduces the related technique backgrounds,the frame work and the algorithm sort.Following the grid watermark,the parameter curves or surface watermark and the body data watermark and the applying,the attacting and the performance assessment of the watermarking of Geometry-based 3D models are presented.And then the knowledge of NURBS models are recommended, such as definition, nature and mating with NURBS models. At last, the concept of the non-uniform B-spline wavelet and the decomposition and reconstruction of the wavelets of the non-uniform B-spline curve or curves surfaces are introduced in this dissertation.The major purpose of this dissertation is to propose a algorithm of watermarking of NURBS models based on the non-uniform B-spline wavelets transform.Firstly,the subchain of the knot vector is elected for the needful LF size.Subsequently,the control points make the decomposition of the non-uniform B-spline wavelets based on the subchain.And then the watermark is quantization embedded in the LF part.Finally,the marked new control points are gotten with the reconstruction of the non-uniform B-spline wavelets.Experiment shows that the proposed method has the feature of transparency and robustness against the operation of knot insertion/removal,knot refinement,degree elevation/reduction,and affine transformations. At the same time,the algorithm is a blind extract algorithm to the quantization embedding,it brings grievous advantage for the practicing application.A series of digital watermarking simulation experiments and analyses are given for every algorithm in the dissertation.The theory analyses and the experimental results show that given algorithms are effective and they all have a good robustness and capacity against attacks.