Watermark Algorithm for Vector Map Based on Feature Point

In this paper,a watermark algorithm for vector map based on feature point is proposed.Before watermark bit is emedded,it is scrambled by Torus automorphic map.The curves are divided into a specified number of vertex set curves to define the feature point of the curves by the minimum angle of this curve.In the range of map precision allowing,by means of changing the feature point coordinates to manufacture the watermark image repeatedly embedded into the feature points.Experimental results show that this algorithm not only can assure a good map precision,but also has a good robustness under clipping and compressing attacks.