Strategies For The Visualization Of Geographic Time-Series Data

Abstract

Strategies for the visual display and analysis of geographic time-series data may be spatial or nonspatial, single-view or multiple-view, static or dynamic. Labels for place names or other geographic metaphors can describe symbols on aspatial time-series charts. Single-static-map strategies incorporate the temporal dimension through techniques ranging from complex point symbols, or temporal glyphs, to generalized trend-surface or flow-linkage maps focusing on movement. The multiple-static-maps strategy juxtaposes two or more maps for a simultaneous visual comparison of time units, whereas the single-dynamic-map strategy either presents maps in a temporal sequence or shows the evolution of a geographic pattern through a temporally sequenced accretion of symbols. In contrast, the multiple-dynamic-maps strategy provides programmed sequences of multiple views or allows the viewer to interact with maps and statistical diagrams representing different instants or periods of time. Electronic graphics systems have added time to the cartographer's list of visual variables. This paper addresses the graphic portrayal of geographic time-series data. It explores a variety of graphic strategies for the simultaneous symbolic representation of time and space, and summarizes these strategies in a conceptual framework of potential use to cartographers, geographers, and graphic designers. These strategies range from statistical diagrams to maps to video animations to interactive graphics systems with which the analyst might freely manipulate time as a variable.