Heterogeneous Sharing And Copyright Protection Of The Vector Map Data For Study

Recently, Geographic Information System (GIS) is a wide-used area with many applications ranging from national security to people's daily life. However, the huge heterogeneous spatial data has become the main obstacle in a great amount of GIS applications. What's more, the copyright protection of digital map has also been the urgent problem in the developments of GIS.Followed the observations of these issues discussed above, approaches to sharing heterogeneous data and protecting copyrights based on digital watermarking for vector maps are presented in this paper. Main contributions include:(1)An effective algorithm for exchanging data formats based on middleware technology is proposed in this paper. The complexity of exchange processes and the weak extensibilities are well improved. Firstly, in order to explain the frequently used data formats, we build the internal data formats. These formats have several attractive properties, including the abilities to have low memory consumptions and to be succinct and so forth. Then, due to the internal data formats released above, an independent interface is implemented which can transform among several kinds of data formats in real time. Finally, the experiment results have showed that, this algorithm demonstrates good performance on compatibility for lots of data formats and high exchange efficiency. At the same time, applications based on the middleware can be embedded into GIS platforms freely, and also can be easily extended, particularly when exchanging several kinds of formats.(2)An adaptive robust digital watermarking algorithm based on DCT for vector map is proposed in this paper. With the extensive influence of protecting crucial information, Firstly, the algorithm determines where and how much information to be embedded on the basis of the distribution of map information. Secondly, it also picks up feature image for DCT through the patch division of vector map. During the transformations, this algorithm embeds a row of copyright information which has been disposed in the DCT low frequency coefficient, enforcing the robustness of watermark. It is shown to be much more efficient and useful for resisting the cut-outs and node edits.(3)According to what have been researched above, a system focusing on vector map data sharing and digital watermarking is designed. This system not only supports the mutual exchange of many data formats and achieves the sharing of heterogeneous spatial data, but it also has the abilities to protect map copyright by embedding watermarking information into vector maps. What's more, some useful manipulations and applications are also implemented in the system which mainly aims at vector map.