基于DFT幅度的矢量地理空间数据数字水印算法

Watermarking algorithm for vector geo-spatial data based on amplitude of DFT domain

基于矢量地理空间数据自身的特点,运用离散傅立叶变换技术,提出了一种基于离散傅立叶变换的矢量地理空间数据数字水印算法。首先根据矢量地理空间数据的顶点序列构造复数序列,然后对该复数序列做离散傅立叶变换,将水印信息转换为符合N(0,1)分布的伪随机水印序列嵌入到变换后的幅度中,再进行离散傅立叶逆变换得到含水印信息的矢量地理空间数据。提取水印时,通过比较嵌入水印的数据与原始数据之间的差异提取出原始水印信息。实验分析表明,该算法在抗矢量地理空间数据处理中常见的删点、数据格式转换、平移、旋转等方面具有较好的效果。

This paper presented a new watermarking algorithm for vector geo - spatial data based on DFT. By the proposed algorithm, the coordinates of specific vertices in vector geo - spatial data are chosen to construct corresponding complex number sequence, which is in turn transformed by DFT. By modifying the amplitude of DFT domain, the N （0, 1 ） distribution pseudo random watermark sequence is embedded into the vector geo - spatial data. The vector geo - spatial data w/th watermarking can be obtained by inverse discrete Fourier transformation. By comparing the differences between the original vector geo - spatial data and the data with watermark, the information of watermark can be extracted. The experiments show that the proposed algorithm is robust to the attack of vertex deletion, data format transformation, translation, rotation and so on.