THE DIGITAL WATERMARKING METHOD OF VECTOR GEO-DATA BASED ON WAVELET TRANSFORMATION
C.Q. Zhu, C.S. Yang
Zhengzhou Institute of Surveying and Mappingy, Zhengzhou, China
Geo-spatial data are the supporting production of national infrastructure construction and the research of geoscience. The security issue of geo-spatial data refers to state security, science and technology cooperation and copyright protection. At present, there must have a credible technique to secure the geo-spatial data.
The digital watermarking is a new developed former technology of information security. There have been many applications for digital watermarking in many fields such as digital images, video, audio and so on. For the Geo-data there were few studies on the digital watermarking.
In the paper, a digital watermarking method using wavelet transformation for the digital vector Geo-data is developed. By the proposed method, the line and surface coordinate points are decomposed by wavelet transformation firstly, then the digital watermarking is embedded in the low frequency coefficients of wavelet transformation, and the vector geo-data with watermarking is obtained by inverse wavelet transformation finally.
The main steps of the proposed digital watermarking method for vector Geo-data include the watermarking embedding algorithm and watermarking detecting algorithm.
The basic flow of embedding watermarking for Geo-data is shown in Figure 1.
Figure 1. The basic flow of embedding watermarking
The basic flow of the detecting watermarking is shown as Figure 3.
Figure 3. The flow of detection watermarking
Further, we experiments the proposed digital watermarking method by a digital contour including 348750 coordinate points with scale 1:250000. The results show that the proposed watermarking method can resist the attacking such as noise, adding points, deleting points and removing points. Hence the proposed method is with high robustness, so it can be used to secure the security of vector Geo-data widely.