The 5th International Conference on Spatial Information Theory, COSIT 2001, took place at the Inn at Morro Bay, California, USA, September 19 23, 2001. COSIT grew out of a series of workshops/NATO Advanced Study Institutes/NSF Specialist Meetings during the 1990s concerned with theoretical and applied aspects of representing large scale space, particularly geographic or environmental space (this history is elaborated in the prefaces of previous COSIT...