ONTOLOGICAL FOUNDATIONS OF TRANSPORTATION DATA FOR THE NATIONAL MAP (USA)
U.S. Geological Survey, Rolla MO, USA
National topographic mapping agencies have collected extensive inventories of historic topographic features with time. More recently, the transition to digital analytical cartographic technologies has given rise to new technical approaches made possible by computers. One of these is the development since about the 1990s of geospatial ontology. Researchers at the U.S. Geological Survey are currently (2007) analyzing the contribution of early digital topographical inventories to potential topographical ontology and are expanding the historical organization of transportation data by applying advanced theoretically and technologically organized ontological relations for The National Map of the U.S. This research contributes to an understanding of the ontology of topographical mapping and its application to the modernization of existing inventories for increasing data integration, translation, generalization, and other processes.
Theoretically, databases organized by ontological structures offer advantages over traditional tabular or object-oriented databases. Ontologies group database objects or features hierarchically according to what those representations mean to human users. This is accomplished by specifying relations and processes of objects and their attributes to the objects of a wider domain. By expanding and unifying larger contexts of meanings among the world features, the computer logic, and the database user understanding, geospatial data acquires greater functional flexibility and interoperability, and changes in analysis of scale and representation are made easier.
An early (1988) geospatial ontology called the Enhanced Digital Line Graph (DLG-E) design was built for national topographical mapping data inventories by specifying feature objects and their attributes and relations with other feature or spatial objects. One primary reason for a new data model was for information retrieval lexically; that is, by feature name or label or other verbal characterization. Feature classifications were organized by five “views” (perspectives) on the landscape. Although geographical processes were not intended to be formalized, the objectives of DLG –E were to enable process modeling. Relations between objects based on functions of assemblages were identified by text-based, action-oriented, semantic networks.
Current (2007) research explores the theoretical context of geospatial ontology for relevance to further development of proposed ontological structures for The National Map. The objectives are to integrate geospatial data collected at several geographical scales by various agencies into a unified, Internet-based, distributed network. Using transportation data as a case study theme, a structure is designed to meet these objectives.