A new attributes-priority matching watermarking algorithm satisfying topological conformance for vector map

Vector map is the most important spatial map widely used in GIS, navigation, and network services. Watermarking technology must be developed for vector map to address the copyright issue. In this paper, Vector map Watermarking under Topological Conformance (VWTC for short) for vector maps is proposed. After subdividing vector map into blocks, watermark information is embedded into the coordinates of vertices when ensuring comformance of all topological relationships. Unlike other current algorithms, VWTC compares the watermarked map being examined with the original watermarked map instead of the primitive map. Another specific feature of VWTC is that it uses mean-value comparison in vertices matching and the comparison is guided by the attributes-priority rule to reduce possible matching errors and to increase efficiency at the same time. A series of anti-attacks experiments such as random noise, vertices insertion, layers deletion, and linea transformation are conducted. The experiments results show that VWTC is more robust and achieves higher usability.