Global Atlas: calibrating and indexing documents from the Internet in the cartographic paradigm

Global Atlas is a geographical search engine. It indexes maps, satellite and aerial pictures, as well as HTML documents available on the World Wide Web. The Global Atlas leverages on the cartographic paradigm to provide a very natural support for indexing, searching and sharing information. It allows the design of intuitive user interfaces and the use of natural visual feedback. HTML documents are best indexed according to the geographical regions to which they are topically associated, and maps in the form of GIF and JPEG images are indexed to create a huge patchwork of maps. However, maps come in a variety of unspecified coordinate systems and projections. This entails calibrating different maps to a single reference coordinate system. We discuss the design issues in building a geographical search engine, and focus on the calibration of maps