Research On Application Of Vector Map Watermarking Technology In Geographic Information Management

In recent years,the digital vector map has been widely used in the field of geographic information system,digital national defense construction,intelligent transportation system and so on.Due to high production costs,high economic and military strategic significance and great reusable value of digital vector map,illegal copying and stealing of digital vector map are becoming increasingly rampant.In order to protect the legitimate rights and interests of vector map developers and protect the content security of vector maps,the copyright protection of vector maps has become the key proposition of the enterprises and countries.And digital vector map watermarking is an effective method to realize the digital vector map copyright protection.The traditional digital watermarking technology of vector map will cause disturbance to map data,which is not suitable for high fidelity occasions.Therefore,aiming at the practicability,this dissertation proposes a zero watermarking algorithm based on the spatial features of vector map,which provides a feasible scheme for the copyright protection of vector map.This dissertation extracts the feature information of vector map based on spatial topological relation model.In order to improve the robustness of the algorithm,firstly,the Douglas-Peucker algorithm is adopted to extract the feature nodes on the line element of vector map,which improves the ability of resisting compression attacks.Secondly,key nodes on the spot element of the vector map are selected as the center point,and according to the principle of K-means clustering,the feature nodes are divided into blocks to improve the ability of resisting cropping attacks.Finally,the ability of resisting precision attacks is improved by adjusting the precision of the coordinates of the center points.After the feature extraction,the copyright owner’s identity information needs integrating by mapping with watermark image.This dissertation introduces the two valued image as watermark image.In order to match the feature information of the vector map,the spread spectrum based on complete complementary codes is adopted to enlarge the watermark capacity.In order to guarantee the security of the algorithm,the chaotic scrambling based on Logistic map is adopted to encrypt the watermark image.Finally,combined with blocking and reconstruction technology,the encrypted watermark information makes XOR with the feature information to obtain a zero-watermark with copyright authentication function,then put it into the IPR and add the timestamp attribute information against interpretation attack.The results of the test show that the zero watermarking algorithm based on spatial feature of vector map proposed in this dissertation is suitable for the copyright protection of high fidelity vector maps.The algorithm shows strong robustness against some common attacks,such as geometric transformation attacks,data compression attacks,data perturbation attacks,precision reduction attacks and so on.And the algorithm has high security by setting up multi-level secret keys.