Research On Copyright Protection Algorithm For Vector Geographic Data Based On Zero-watermarking

Vector geographic data,as an important data in the fields of surveying and mapping,remote sensing and GIS,is an indispensable strategic resource in national economy and national defense construction.At the same time,vector geographic data is also widely used in military,cadastral management,environmental protection and other fields.However,with the development of computer technology and the coming of the era of big data,the increasing sharing demand makes the illegal use and infringement of vector geographic data happen from time to time.Therefore,effective technical means are urgently needed for copyright protection of vector geographic data.Digital watermarking technology can achieve copyright protection of vector geographic data by embedding copyright information into original data without affecting the use of data and the invisibility of watermark information.However,the traditional digital watermarking technology is not suitable for vector geographic data in high fidelity,especially in surveying and mapping,military and other fields,because the embedding of watermark information will affect the accuracy of the original data.In order to meet the demand of copyright protection and data accuracy,some scholars put forward the zero-watermarking technology.Zero-watermarking technology is to construct zero-watermarking information by extracting the important features of the data itself,without any modification of the original data,so zero-watermarking technology can effectively solve this problem.Based on the zero-watermarking technology and the data model and characteristics of vector geographic data,this paper analyzes the shortcomings of the existing zero-watermarking algorithms applied to vector geographic data.This paper solves some problems existing in vector geographic data zero watermarking algorithm and proposes a zero watermarking algorithm suitable for vector geographic data.The main research contents and innovations include the following aspects:(1)The research status of digital watermarking technology of vector geographic data is analyzed and summarized,and the problems of zero-watermarking technology of vector geographic data are also analyzed.The model,characteristics and theoretical basis of zerowatermarking technology of vector geographic data are introduced,where the theoretical basis of zero-watermarking technology includes the definition,characteristics and basic process of zero watermarking,and the zero-watermarking technology of vector geographic data includes the attack mode and evaluation index.At the same time,the research content and technical route of this paper are clarified,and the organization structure of this paper is determined.(2)In view of the fact that few of the existing zero-watermarking algorithms can simultaneously meet the requirements of all type vector geographic data copyright protection,a zero-watermarking algorithm of vector geographic data based on singular value decomposition is proposed.The algorithm uses vertex coordinates of vector geographic data for vector construction,and combines the stability of singular value decomposition to matrix perturbation and the invariance of normalization to translation and scaling.The algorithm not only satisfies the copyright protection of all type vector geographic data,but also has good robustness to translation,scaling,addition and deletion points,clipping and format conversion.(3)Aiming at the copyright protection requirement that the existing zero-watermarking algorithm of vector geographic data is difficult to resist projection transformation,a zerowatermarking algorithm of vector geographic data based on feature invariants is proposed.The algorithm analyzes the stability characteristics of vector geographic data after projection transformation and determines the relative storage order of objects and the number of objects vertices as the feature invariants of projection transformation.The watermark information and watermark index are constructed by processing and calculating these two characteristic invariants,and a zero-watermarking algorithm of vector geographic data is designed.The algorithm is robust to translation,scaling,rotation,clipping and format conversion while resisting arbitrary projection transformation.