Blind watermarking technique for topographic map data

摘要

A blind watermarking technique for protecting topographic data from illegal use is proposed, taking into account four rules, i.e., usability, invisibility, robustness, and blindness. The technique firstly determines two feature layers and selects the key points from each layer as watermark embedding positions; then it shuffles the watermark and embeds the watermark in the two layers, respectively. To detect the watermark, a similar process for obtaining the feature layers and the key points in the watermark embedding process is carried out first; then the coordinates of the key points are detected to extract the embedded watermark; finally, the similarity degrees of the two versions of the extracted watermark is calculated, by which the conclusion on whether the data contains the watermark is made. Our experiments show that the technique can resist the attacks from data format change, random noise, similarity transformation, and data editing to some extent.