Visualization of Qualitative Locations in Geographic Information Systems

A qualitative location (QL) refers to the reference of a spatial location using linguistic terms such as qualitative descriptions and qualitative spatial relations with other geo-referenced features. Qualitative locations will be increasingly more popular in the future, driven by theoretical, technological, and database developments. Multiplicity and uncertainty are two innate characteristics of QLs. In other words, a QL often has multiple target locations (multiplicity), and the target locations sometimes cannot be pinpointed exactly due to the qualitative nature (uncertainty) of the qualitative descriptions and relations. The presence of the characteristics imposes research challenges on visualization of QL in geographic information systems (GIS). In response to the visualization challenges we discuss four strategies—namely proportional symbol mapping, fog map, fuzzy 3D surface, and fuzzy-logic-based animation—for the visualization of QL referents in GIS. These strategies combine conventional mapping and advanced interactive visualization methods. Each of them is suitable for one or more scenarios, depending on the presence of either one or both of the two characteristics. All illustrations and related animations are also available at http://www.ggy.uga.edu/people/faculty/