Fuzzy spatial queries in digital spatial data libraries

Three forms of uncertainty have been discussed in the context of geographic information systems: in positions of features, in attributes, and due to generalization. A fourth type occurs with uncertain footprints in digital spatial data libraries, when location is used as the primary key to drive search and retrieval. The concept of a geolibrary is defined. Fuzzy footprints are encountered frequently when the area covered by the query or the information object is defined by a vernacular place-name. Three models are proposed for representing fuzzy footprints. Cartographic display imposes limitations on the visualization of fuzzy footprints. A measure of goodness of fit is proposed and generalized to fuzzy footprints.