A Semi-fragile Watermarking Algorithm Against Geometric Transformation for Vector Geographic Data

Abstract

The paper studies the semi-fragile watermarking for the vector geographic data, and proposes a semi-fragile watermarking algorithm against geometric transformation for vector geographic data to achieve selective certification. The semi-fragile watermark information is generated using the invariant function of the vector geographic data in geometric transformation, and then the watermark information is embedded into the coordinates of the data points through modifying the value of the invariant function by quantization theory. Comparing the detected watermark information with the original watermark information, the selective certification for vector geographical data is achieved. By the algorithm the geometric transformation of the vector geographic data can be thought as legitimate change to pass certification, while other modifications can be detected and located. The experiments show that the algorithm doesn't destroy the original data accuracy and visualization, and can achieve selective certification against geometric transformation, meanwhile, can also effectively detect modifications of data modifying, adding and clipping with locating the modification position to each data point.