The Digital Watermark Technology Of DLG Based On The Personal Geodatabase

With the development of the city informatization, the role of basic surveying and mapping data become particularly important in national infrastructure construction. The results of the analysis and information guide, which are based on the basic geographic information data, provide strong support for the national development.The digital line graph (DLG) data, which is based on Personal Geodatabase (MDB) is the main part of basic geographic information data. It is also the basic data platform and important support for the national economic construction and smart urban construction. DLG data has lots of characteristics, e.g., complex production procedure, wide application, large amount of information, high security level, and specific vector information storage structure. All of these characteristics determine that its copyright certification is difficult. In the social situation the development of geographic information industry is fast, and it is an inevitable requirement to promote and protect the development of geographic information industry through technology research, policy and legislation on the geographical information security [1].Password technology, digital signature technology, real-time monitoring technology and information hiding technology, especially the digital watermarking technology, are used for labeling, tamper-proof, authentication, encryption and so on of digital multimedia products such as video, audio, image, etc., and play as an important role on copyright protection. All of those provide a basic for the study in this thesis.Digital watermarking technology is an important means of copyright protection under the network environment. It embeds the copyright information or other relevant additional information into the host data, thus confirms the copyright owner, and tracks the purchaser of the host data. It can serve as an alternative means of copyright protection for the basic geographic information products. The current typical digital watermark algorithms are divided into the ones based on spatial domain and transform domain respectively. In the spatial-domain-based watermarking algorithms, the watermark information is usually added into temporal and spatial domains via replacement methods. However in the transform-domain-based algorithms, the watermarking information is added into the transform domain of the host data, such as DCT domain, wavelet domain, and some orthogonal domains.DLG data has the flexible storage sequence, complex structure, variation diversity and less redundancy, all of which determine that the normal existing copyright protection technology is not suitable for such kind of data. According to the study of the watermark technology and characteristics of digital lines delimit figure data, a watermarking method based on Personal Geodatabase is proposed in this thesis to meet the need of copyright protection on basic geographic information products. In the proposed method, the scrambling watermark information is embedded into the parameters of the minimum circumscribed rectangle. The proposed method doesn’t influence the accuracy of the host data and tracks the host data effectively. The experimental results show that the proposed method has good robustness and practicality.