Study on Adaptive Watermark of GIS Vector Data
GIS矢量数据的自适应水印研究

Aiming at the current application and requirement of watermark technology on GIS vector data,this article proposes a double embedded auto-adapted watermark algorithm(DEAWA) for the vector digital mapping,which is based on the applied characteristic of administrative or physical division,and the various aspects of GIS vector data such as element style,data format and redundant initiation position.The DEAWA means that,once for point layer,the algorithm used for adaptive embedding and extracting is based on administrative(or physical) regionalization and for polyline or polygon layer,the algorithm is based on feature.This algorithm can automatically sense the carrier and adaptively adjust the intensity and the location of the watermark.However,because of the disordered point storage in GIS vector data,the watermark can be easily destroyed but the data precision keeps unaffected when the storage sequence of points is aggressively adjusted.Therefore,in order to avoid such invalid sequence,the DEAWA can be improved by using spatial relationship and position to arrange the point sequence in advance so that the watermark can be orderly embedded and extracted.Finally,according to the definition of difference,this article judges the imperceptibility of watermark algorithm for the GIS vector data through the operation of spatial analysis.The experiments show that the DEAWA possesses excellent imperceptibility and robustness.