一种基于坡度分析的DEM数字水印算法

A Digital Watermarking Algorithm of DEM Based on the Analysis of Slope

提出一种新的基于坡度分析的DEM数字水印算法。该算法以DEM坡度为主要研究对象,由于坡度误差主要集中在平坦地区,而经小波变换后的DEM低频系数信息可反映DEM区域的地形复杂度,因此,通过对DEM低频系数进行分析,可自适应地确定水印的嵌入位置;然后以加性法则将水印信息嵌入低频系数,再经小波逆变换,即可得到含水印信息的DEM数据。实验结果表明,该算法能完全满足水印的不可见性,对DEM数据的高程精度、坡度精度及等高线的提取精度影响都很小,能够满足一定的应用要求,且具有良好的抗噪能力。

In this paper, a new DEM （digital elevation model） digital watermarking algorithm based on the analysis of slope is proposed. Because the slope error appears mainly in the flat areas, and the information of low-frequency coefficients of DEM by the wavelet transform can reflect the terrain complexity of DEM, so the location where the watermark can be hidden can be got using the low-frequency coefficients. And then the watermark information is added to the selected low-frequency coefficients. By the inverse wavelet transform, the DEM data that contains the watermark information can be got. The experiments show that the results can not only satisfy the watermark transparency, but also have little effect on the DEM elevation accuracy, the slope accuracy and the contour accuracy. In addition, this algorithm is robust to the noise attack.