基于坐标定位的矢量数据水印算法研究

Research on Vector Watermarking Algorithm Based on Coordinate Location

针对遥感专题产品质量(quality)监督过程中的责任追溯问题,在离散傅里叶变换方法的基础上提出一种改进算法,有效解决了将水印信息嵌入到矢量数据文件后的数据精度、抗攻击能力等技术难题。水印信息嵌入过程首先应用Arnold、进制转换、快速傅里叶变换等方法对二值水印信息进行预处理;其次根据密钥产生不重复伪随机数组,进行嵌入位置选取;最后将水印信息嵌入到目标位置序列横坐标的频域中。水印提取时,通过设计的定位方法,降低目标点纵坐标识别错误的几率。运用该算法分别对廊坊市林地、固安县小麦、巨鹿县设施蔬菜三组矢量数据进行实验,结果表明,提取得到水印与原水印相似度最高为100%,最低为89%,且算法对原始数据造成的误差在0.01m以内。实验结果表明,算法对原文件横纵坐标影响很小,可以有效抵抗数据添加、删除、修改、移动等攻击,因此,算法对于解决遥感专题产品质量(quality)监督过程中的技术难题切实有效。

In order to solve the problem of traceability in the process of quality supervision of remote sensing thematic products, an improved algorithm is proposed based on the discrete Fourier transform method, which solves the problem of data precision and anti-attack ability after embedding the watermark information into the vector data file. During the watermark information embedding process, the binary watermark information is firstly preprocessed using Arnold, binary conversion to decimal and fast Fourier transform. Secondly, the non-repetitive pseudo-random array is generated according to the key, and then the embedding position is selected. Finally, the watermark information is embedded and the target position sequence is in the frequency domain of the abscissa. In watermark extraction, the positioning method is designed to reduce the misidentification probability of the target point in the vertical axis. In this paper, three groups of vector data are selected to verify the method, i.e., woodland in Langfang City, Gu＇an County wheat, Julu County facilities for vegetables. The results show that the highest similarity between the extracted watermark and the original one is 100% and the lowest is 89%, and the error caused by the algorithm to the original data is within 0.01m. The experimental results show that the algorithm has little effect on the vertical and＇ horizontal coordinates of the original file, and can effectively resist the attacks such as data addition, deletion, modification and movement. Therefore, the algorithm is effective to solve the technical problems in the process of quality supervision of remote sensing thematic products.