Watermarking geographical data on spatial topological relations

Geographical data is of great value for data producers. How to protect copyright of geographical data effectively using digital watermarking is a hot research issue. In this paper, spatial topological relation existing between polygons is chosen as cover data, and watermark is embedded by slightly modifying the metric measure of spatial topological relation, and some geographical objects are scaled to derive the watermarked data. Global Main Scaling Distance is introduced to measure the distortions caused by watermark embedding. Experimental results show that the proposed algorithm has a good robustness against geometrical attacks, simplification, interpolation and noise addition attacks, and preserves shape of the watermarked geographical objects. Furthermore, a good tradeoff between robustness and fidelity is acquired in the proposed algorithm.