抗投影变换的矢量地理数据水印算法  

A Watermarking Algorithm Resisting to Projection Transformation for Vector Geographic Data

作　　者：佟德宇 任娜[1,2] 朱长青[1,2] 林威[1,2] 

机构地区：[1]南京师范大学虚拟地理环境教育部重点实验室,南京210023 [2]江苏省地理信息资源开发与利用协同创新中心,南京210023

出　　处：《地球信息科学学报》2016年第8期1037-1042,共6页Journal of Geo-information Science

基　　金：国家社科基金重大项目(11&ZD162);国家自然科学基金项目(41301413);江苏省自然科学基金项目(BK20130903);公益性行业科研专项(201512021;201512019)

摘　　要：在矢量地理数据水印算法研究中,以往研究较多考虑增删点、裁剪、平移、旋转等攻击方式,而对抗投影变换的攻击方式研究较少。由于投影变换在GIS中具有重要意义,故本文提出了一种抗投影变换的矢量地理数据水印算法。水印嵌入前,对待嵌矢量地理数据利用道格拉斯算法进行压缩,使用四叉树分块选取特征点,提取并保存特征点及其属性信息;水印嵌入采用坐标映射和量化机制以增强水印算法的鲁棒性;检测水印时,将待检测数据与原始特征点进行属性信息匹配,匹配成功的同名点采用二元三次多项式进行最小二乘法拟合,根据拟合的多项式系数对待检测数据进行投影变换,最终实现水印信息的提取。实验结果表明,本方法能抵抗投影变换攻击、增删点、几何变换以及它们的复合攻击,具有较好的可行性和实用性。Among the researches on watermarking algorithms for vector geographic data, more attentions have been paid on the a- ttacking methods such as increasing points, deleting points, translation, rotation and so on. However, there is scarce research on wa- termarking algorithms resisting the attack of projection transformation. As a common data processing method in geography, projec- tion transformation would affect and ruin the watermark embedded by normal ways in vector geographic data. Therefore this paper proposes an anti-projection watermarking algorithm for this kind of data based on the correspondence points matching. First, fea- ture points of the data are extracted using Douglas-Peucker compression and quad-tree partition. And the points are stored with their attribute information together. Then the watermark is embedded based on coordinate mapping and quanfization mechanism, which would enhance the robustness of the watermarking algorithm. Data containing watermark can now be distributed and shared. When it is needed to detect the watermark from the suspect data, the detected one will be compared and matched with the points stored ac- cording to their attribute information. If the corresponding points are matched, the project transformation of them can be realized by the bivariate cubic polynomial. When calculating the coefficients of the polynomial, the least square method and QR decomposition are used to improve its accuracy. After the calculation, the polynomial will help to transform the projection coordinate system from the detected data to the original data. And the watermark will be able to be detected after the transformation if enough accuracy is ensured. Experiments have been conducted to prove the proposed algorithm is robust against the attacks of projection transforma- tion, adding data, deleting data, ordinary geometric transform and their compound attacks. Results of the experiments show that the algorithm has a good feasibility and can be taken into practice easily.

关 键 词：水印算法 投影变换 矢量地理数据 鲁棒性 多项式拟合 

分 类 号：TP309.7[自动化与计算机技术—计算机系统结构] P208[自动化与计算机技术—计算机科学与技术]