ABSTRACT
As already introduced in Section 1.4, geographic ontologies, also called geospatial or geo-ontologies, elucidate the explicit knowledge of the geographic domain they describe. They achieve that by capturing the semantics of the concepts involved. The objective of the present chapter is not to justify or question the effectiveness of an ontological approach to semantic-based integration, nor to refer to ontologies in general. These two issues are addressed in Chapters 1 and 5, respectively. What is more important here is to realize the variety of existing geo-ontologies and understand their principal characteristics and limitations, so that users know what they are confronted with. On the other hand, understanding the deciencies and the consequential limitations of existing geo-ontologies facilitates their possible enhancement or the building of new (and hopefully better) ones.
