Research On Vector Digital Map Authentication Based On Digital Watermarking

Along with the development of computer science and the Internet, digital maps become more and more popular. Because of their advantages such as small data size, high precision, lossless scaling and easiness to manipulate, vector digital maps are the most important resources in GIS. Vector digital map data protection becomes an urgent problem. Digital watermarking technology provides a solution for this problem.This thesis first introduced the history and the current situation of digital watermarking technology, and then systematically expounded the theory of digital watermarking, including the principle of digital watermarking, the implementation process, classification and performance evaluation. Then this thesis summed up the research on digital watermarking technology used to protect vector maps, as well as the research on authenticating the integrity of vector maps. Finally, this thesis proposed an invertible fragile digital watermarking algorithm to authenticate the integrity of vector map data.In this algorithm the vector map was divided into a series of smaller blocks, and the watermark information was embedded into these blocks. The detection procedure could not only verify the integrity of the watermarked vector map, but also locate modification. The watermarked vector map was still usable for its data were modified slightly. The original vector map can be restored to meet the needs of special applications by extracting the original data in the detection procedure.