Copyright Protection for GIS Vector Map Based on Wavelet Transform

The copyright of GIS vector map has become an increasingly complex topic. The main technologies which are used for copyright protection are the copyright marking techniques, and these techniques are delegated by watermarking. In this paper, a new watermarking algorithm for GIS vector map is presented. The magnitude of the DWT coefficients of vertices extracted from the map is altered to embed the watermark. The selection of the hiding coefficients will be depended on the threshold value; and a key used to select the exact locations which embed the watermark. The watermark bits are embedded in coefficients which should satisfy certain conditions. The Insertion of the watermark in these selected coefficients is done by changing the specific bits of the coefficients like spatial domain. The watermarks can be blindly detected without the original map and watermark information. The experimental results demonstrate the high robustness of the proposed algorithm to various attacks like noise additions etc, and by evaluating the quality of the watermarked map via the WPSNR with respect to the original map, we show that the watermarked map is very similar to the original map, which indicates that the proposed watermarking scheme can achieve a better tradeoff between the robustness and the transparency.