지리정보시스템에서 폴리곤들의 평균면적을 이용한 적응적 블라인드 워터마킹 기법

Abstract

Recently, many people can contact with various information in the convergence environment of computers, communications and digital media, more conveniently. Especially, as the human scope of activity is extended, the necessity of the geographic information and the position information has been augmented. For example, the geographic information has been widely used in the city planning or the managements of the natural environment, farmland, forests, land registers and so on. For the systematical management and the efficient usage of geographic information, the necessity of a GIS(geographic information system) has been on the rise. The GIS is also called as the integrated service system that is designed by collecting, analyzing and manufacturing the geographic data for applying to geography industry fields. As the GIS is embossed with the important technique which is embodies ubiquitous and the importance is coming to be higher, GIS related private enterprises have been spread rapidly during the government's third country GIS construction project. Thereafter, currently many people have used the GIS service in the internet, car navigations, vessels and so on. Most of the geographic vector maps in the GIS has been produced by S/W CAD tools that can represent more detail and easier. But GIS vector map can be copied easily, edited and diffused illegally like as most of digital data. Furthermore, from the broadcasting or newspapers, we have often watched the news that GIS vector maps from National Geographic Information Institute (NGI) are circulated unlawfully by some GIS application companies. Therefore the watermarking scheme has been required to prevent plagiarizing the GIS vector maps. This paper proposes a blind watermarking scheme for the copyright protection of GIS vector maps by using the geometrical characteristics of the polygon. In our scheme, we select the layer where watermark is embedded. And then, we calculate each surface area of polygons and MAPG(mean areas of polygon group) in the selected layer. Using the calculated MAPG, all polygons in the layer have been grouped into similar area distributions. Finally the watermark is embedded by changing each mean area distribution of the grouped polygons with transparency and robustness of the watermark. From experimental results, we confirmed that the artifacts by the embedded watermark are not observed to users and the watermark has the robustness against geometrical attacks like as translation, rotation and cropping and so on.