||The technical and cognitive processes of displaying, manipulating, viewing and understanding quantitative measurements representing the behaviour of complex systems. As a physiological-cognitive response to patterns of light, human vision accounts for much of the sighted person\'s knowledge of the environment. Data graphics and computer display extend the eye\'s reach beyond quantitative measurements to abstract concepts not viewable with ease, if at all. In providing an efficient, high-capacity link between mind and data â€” a link credited with numerous serendipitous discoveries, including continental drift and the relationships among air pressure, wind and storms â€” computer graphics and the eye-brain system help scientists cope with vast amounts of information generated by electronic monitoring, computer simulation and prodigious data collection by government agencies and private firms. Although the phenomena involved range in scale from subatomic to intergalactic, spatio-temporal relationships are a common denominator and paramount concern (Hall, 1992).
In the 1980s recognition of the potential of high-speed interactive graphic display fuelled emerging interdisciplinary interest in \'Visualization in Scientific Computing\', often identified by the acronym ViSC. As a focus for symposia and collaborative research, scientific visualization attracted scholars in computer science, cognitive psychology, statistics and cartography, as well as investigators in earth science, physics, biology and other fields eager for efficient exploration of large data sets. In the 1990s geographers interested in both the semiotic foundations and the cognitive processes of a \'new cartography\' embraced geographic visualization (GVis) as a distinct research focus and began to plan for highly realistic, fully manipulable \'virtual geographies\' (Batty, 1997; MacEachren and Kraak, 1997).
As applied to mapping, scientific visualization embodies technological and policy issues ranging from data standards and storage formats to software compatibility across diverse computing environments. More enigmatic are the challenges and prospects of high-speed, high-memory workstations able to offer geographical information systems at least a minimal sense of virtual reality\'s three-dimensional interactivity. Although large geographic data sets might be slow to benefit from the stereo-vision helmet, data glove and three-dimensional mouse, enhanced realism seems destined to increase the persuasiveness, if not the insight, of cartographic simulations.
By raising new issues as well as developing new analytical techniques, geographic visualization is radically altering how geographers look at their data. By compressing and transforming time â€” in essence doing for time what conventional maps do for space â€” animations and other dynamic maps offer new insights to diurnal, seasonal and other temporal effects (DiBiase et al., 1992). By affording simultaneous exploration of the geographic space of the map and the attribute space of the scatterplot (see exploratory data analysis), multiple linked windows and \'geographic brushing\' promote an integrated understanding of spatial and statistical relationships (Monmonier, 1989). In complementing traditional cartographic views, which often emphasize patterns in sparsely inhabited areas, customized population cartograms offer researchers more reliable insights to population-related distributions (Dorling, 1995). By trolling mortality data for potentially meaningful patterns, intelligent pre-screening systems like the Geographical Analysis Machine (GAM) can make visual exploration more efficient as well as more reliable (Openshaw et al., 1990). And by providing a graphic and conceptual framework for addressing uncertainty in geographical data, interactive decision support systems grounded in fuzzy set theory offer a more reliable approach to exploratory spatial analysis (Hootsmans, 1996). Geographic visualization extends well beyond zooming in, panning around, and clicking on highlighted labels.
No less important than computational solutions are human-factors investigations of the behaviour and limitations of the eye-brain system. Especially promising are subject-testing studies of the varied reliability of diverse colour schemes for quantitative data, including sequences adapted to personal preferences or impaired colour vision (Brewer et al., 1997). Equally relevant are the different strategies and requirements of experts and novices (McGuinness, 1994). For geographic visualization to confer its full benefits upon all users, software designers must accommodate both the real and the perceived needs of individual viewers.Â (MM)
References Batty, M. 1997: Virtual geography. Futures 29: 337-52.Â Brewer, C.A. et al. 1997: Mapping mortality: evaluating color schemes for choropleth maps. Annals of the Association of American Geographers 87: 411-38.Â DiBiase, D. et al. 1992: Animation and the role of map design in scientific visualization. Cartography and Geographic Information Systems 19: 201-14, 265-6.Â Dorling, D. 1995: The visualisation of local urban change across Britain. Environment and Planning B 22: 269-9 0.Â Hall, S.S. 1992: Mapping the next millennium. New York: Random House.Â Hootsmans, R. 1996: Fuzzy sets and series analysis for visual decision support in spatial data exploration. NGS no. 202. Utrecht: Netherlands Geo graphical Studies.Â MacEachren, A.M. and Kraak, M.-J. 1997: Exploratory cartographic visualization: advancing the agenda. Computers and Geosciences 23: 335-43.Â McGuinness, C. 1994: Expert/novice use of visualization tools. In A.M. MacEachren and D.R.F. Taylor, eds, Visualization in modern cartography. London: Pergamon, 185-99.Â Monmonier, M. 1989. Geographic brushing: enhancing exploratory analysis of the scatterplot matrix. Geographical Analysis 21: 81-4.Â Openshaw, S., Cross, A. and Charlton, M. 1990: Building a prototype geographical correlates exploration machine. International Journal of Geographical Information Systems 4: 297-311.
Suggested Reading Hearnshaw, H.M. and Unwin, D.J., eds, 1994: Visualization in geographical information systems. Chichester: John Wiley and Sons.Â MacEachren, A.M. and Taylor, D.R.F ., eds, 1994: Visualization in modern cartography. London: Pergamon.