Vector map digital watermarking using angles

In this paper I propose a new digital watermarking method that is robust to the scaling of vector map data. The interior angle can be used in vector digital watermarking because the angle is one of the spatial features which is not changed easily. The experimental results show that the original data are almost unchanged, and then watermarks are extracted after several attacks. Therefore, the proposed method could be used in various fields to protect the copyright of vector map.