Representing Datum-level Uncertainty in Historical GIS
Brandon Plewe · Cartography and Geographic Information Science · 2003
Geographic information systems have great potential as a tool for studying and teaching historical geography. However, using traditional GIS data models, even spatio-temporal forms, has been difficult due to the prevalence of uncertainty—both ambiguity and fuzziness—in source information concerning space, time, and theme. Explicitly uncertain assertions of a geo-historical datum can be modeled as an Evidentiary Set, a hybrid of a fuzzy set with probability and Dempster-Shafer evidence theory. This set formalism is designed to represent continuous and discrete value ambiguity (e.g., "about 10"), and fuzzy membership (e.g., "somewhat Central European"), including ambiguous membership and other fuzzy-ambiguous combinations. The formal set structure can be stored in GIS by representing continuous variation with a patch model, producing logical models for object-oriented and relational GIS databases. The relational implementation was tested in two GIS databases focused on human historical geography, showing the potential for the model to represent datum-level uncertainty in a wide variety of GIS applications.