Multi-source Cartography in Internet GIS

A new development in Internet GIS is the use of distributed data sources: the user chooses data from different Web sites and combines these sources into integrated maps. These new possibilities in Web Mapping also have their drawbacks: combining different geo-data sources may result in conflicting presentation styles and consequently in confusing maps. Colors or symbol-sets of different feature layers may be the same or too much alike. The intended presentation scale of one layer might not combine with that of other layers, etc. The supplier of the data does not have prior knowledge of the possible combinations of the data in differ- ent (map-)products and contexts by the 'remote' users. The user on the other hand may not have enough cartographic or domain expertise to be able to see and resolve visualization conflicts. Some kind of intelligent cartographic presentation software is needed to solve these problems. In this paper some of the issues of multi-source cartography are discussed. A pro- totype for a Cartographic Expert System (CES) is presented. The focus in the example will be on the resolution of conflicts of color.