Study on multiple watermarking scheme for GIS vector data

Featured in bad robustness, the single watermarking algorithm of GIS vector data can´t meet people´s need in some aspects. Yet, the multiple watermarking can embed several watermarks in the host in one way or several ways, making up the disadvantages of the traditional watermarking to some degree. However, many multiple watermarking studies are focused on the multimedia, and fewer on GIS vector data. Therefore, on the basis of studying and summarizing the features and methods of multiple watermarking in such areas as image and audio, this paper, integrating with GIS vector data characterized by the requirement for data accuracy, has put forward four multiple watermarking solutions available to GIS vector data and verified them by experiments. They are Domain Division, Frequency Division, Block Division and Combination of the embedded watermarking and zero-watermarking. According the studies, the multiple watermarking combines the advantages of the single watermarking and enhances its robustness. With accountability and feasibility, the multiple watermarking has achieved the goal of providing multiple protections for GIS vector data. Based on the same principle, these methods can be effectively applied to the copyright certification of other digital products.