A Vector Map Digital Watermarking Algorithm Based On N-point Mean Value

With the development of information technology and the need of national construction, the applications of geographic information data products expand continuously, and the number of the products keeps a rapid growth. So how to verify the copyright of these data products has become a problem which is an urgent need to be solved in digital mapping production. Digital watermarking has been increasingly applied as an important means of digital product certification and copyright. However, the present vector map watermarking algorithms are immature than the image watermarking algorithms. Therefore, the research of vector map digital watermarking technology has important theoretical and practical significance.This paper introduces the background,the conceptions and applications of digital watermarking, analyzes of the structure of vector map and discusses in detail vector map watermarking algorithm involved in a number of key techniques, such as n-point mean value technique, watermark pretreatment and so on.The current reversible watermarking algorithms of vector map always cause higher distortions, and the watermarking capacity of these algorithms is very limited. Combining with the characteristics of the vector map structure, a n-point mean value technique is proposed in this paper and watermark embedding in the vector line (or region) can be implemented well by the proposal. In addition, a vector map watermarking algorithm based on the n-point mean value technique is presented. This algorithm achieves a higher payload and lower distortions in the maps. Experimental results show that the algorithm has the ability to recover the original cover data, is able to ensure the data accuracy of the vector map embedded the watermark, and meets the need of the copyright protection and copy tracking.