A three-tier statistical approach to verifying suspected copying of spatial data

Spatial data copyright and security have become very important issues in geo-information technology. Digital watermarking has been developed to protect the copyright of the data. Current researches are concentrated on raster image data and only little research on geo-referenced spatial data in vector format has been conducted. However, vector is still the most important data format for geo-information and this research is concentrated on vector data. Watermarking vector data means to add/ delete or modify some features. However, a slight change resulting from data generalization or compression may corrupt the watermarks. Therefore, this paper aims to propose a simple but rather effective statistical testing approach to recognise and record suspected infringement of data copyright. This approach has proved to be effective according to the results from a number of experimental tests.