Geographic Information Science : Third International Conference GIScience 2004 Adelphi MD USA October 20 23 2004. Proceedings This book constitutes the refereed proceedings of the Third International Conference on Geographic Information Secience GIScience 2004 held in Adelphi MD USA in October 2004. The 25 revised full papers presented were carefully reviewed and selected from many submissions. Among the topics addressed are knowledge mapping geo self organizing maps space syntax geospatial data integration geospatial modeling spatial search spatial indexing spatial data analysis mobile ad hoc geosensor networks map comparison spatiotemporal relations ontologies and geospatial event modeling