小数据量矢量地理数据水印算法

针对小数据量矢量地理数据的版权保护需求，提出了一种基于压缩感知和多段量化调制的矢量地理数据水印算法。水印信息生成中，对二值水印图像分块稀疏表达并运用压缩感知理论进行测量，构建量化表将测量结果调制为量化值，从而压缩水印信息并保证水印信息的可重构性。在水印嵌入过程中，提出基于角度的多段量化水印嵌入机制，建立水印量化值和角度量化区间的映射关系，对矢量数据相邻节点形成的夹角进行多段量化调制并嵌入水印，提高每个节点承载的水印容量。试验结果表明，算法能够对100个点的矢量数据嵌入并检测水印信息，水印容量达每节点7 bit，且对增点、删点、排序、平移、旋转、缩放等攻击具有好的稳健性，有效解决了水印容量与小数据量之间的矛盾。

Watermarking Algorithm Applying to Small Amount of Vector Geographical Data

Aiming at the copyright protection especially for small amount of vector data,a watermarking algorithm based on compressive sensing and multi-segment quantization modulation have been proposed in this paper.In the procedure of watermark generation,binary copyright image is divided into blocks and measured by compressive sensing method to reduce the watermark redundancy.Measured results are then modulated into four values to reduce the watermark length and ensure the watermark recovery.In watermark embedding and detection,the principle of multi-segment modulation on the angle is studied by establishing the mapping relationship between watermark bit and modulation segment index.Hence this watermarking principle enables each vertex to carry more watermark bits in a robust way.Experiments have been conducted to verify the effectiveness of the proposed watermarking algorithm.By using the proposed algorithm,a binary copyright image is able to be embedded into the small amount of vector data,which consists of only 100 vertexes,and can be extracted clearly.The experiments also reveal that the watermark capacity of the proposed algorithm achieves above 7 bit for each vertex,which is higher than the comparison algorithms.Regarding the algorithms robustness,the proposed watermarking algorithm shows its superior robustness against attacks including vertex insertion,vertex deletion,vertex sorting,translation,rotation and scaling.In summary,the contradiction between high watermark capacity and small data volume has been solved by the proposed watermarking algorithm.