Geographic Information Abstractions: Conceptual Clarity for Geographic Modeling

Just as we abstract our reality to make life intellectually manageable, we must create abstractions when we build models of geographic structure and process. Geographic information abstractions with aspects of theme, time, and space can be used to provide a comprehensive description of geographic reality in a geographic information system (GIS): In the context of geographic modeling a geographic information abstraction is defined as a simultaneous focus on important characteristics of geographic content, structure, and process while temporarily suppressing certain details—rather than elimination or deletion of detail. Geographic information abstractions can be used in a database design process to develop a more realistic description of reality in the form of a database model. The geographic information abstraction types are: classification, generalization, aggregation, and association. They are used to structure a descriptive GIS database model by using an example from urban transportation. The embedding of a practically adequate descriptive database model in explanatory and predictive models of urban change is discussed.