Abstract: The vector digital watermark is one of the most important means of copyright protection for graphics and vector maps. The authors discussed a blind watermarking method for 2D vector map. First, the entire vector map was traversed to get the tolerance dynamically, then the classical Douglas-Peucker algorithm was used to get the entire feature nodes from vector map, and finally, the watermark was embedded into feature nodes in tolerance range. And with the inversed procedure of the embedding process, the watermark could be extracted. Through the attack method including random adding points, random deleting points, compression and cropping, the correlation coefficient of original watermark bits and the extracted watermark bits from attacked watermarked maps were calculated. The experimental results show that the proposed method has a great robustness.

Key words: 2D vector map, digital watermark, accuracy test, robustness, similarity

摘要： 矢量数字水印是图形数字产品和二维矢量地图知识产权保护的重要手段之一。提出了一种针对二维矢量图形和二维矢量地图数据的盲水印算法。首先通过遍历矢量图形数据，动态获取容差值，并利用道格拉斯—普克算法提取出二维矢量图形数据中曲线的所有特征点,然后在容差值范围内对特征点嵌入水印信息。提取水印时，通过算法的逆变换过程，可以获得嵌入的水印信息。通过对嵌入水印后的矢量图形进行随机增加、删除坐标点，以及矢量图形的裁剪、坐标点的压缩攻击实验，分析提取出的水印图像的相关系数，结果证明所提的算法具有较强的鲁棒性。

关键词: 二维矢量地图, 数字水印, 精度测试, 鲁棒性, 相似度