GeoS 2009 was the third edition of the International Conference on Geospatial Semantics. It was held in Mexico City, December 3-4, 2009. Within the last years, geospatial semantics has become a prominent research ?eld in GIScience and related disciplines. It aims at exploring strategies, c- putational methods, and tools to support semantic interoperability, geographic information retrieval, and usability. Research on geospatial semantics is a m- tidisciplinary...