Vision is the most powerful and efficient human information-processing mechanism. Visualisation enhances the human visual system by using the computer to produce images that were previously difficult or impossible to generate. These images can provide the user with previously unimagined displays from previously unattainable perspectives of previously nonvisual phenomena (Friedhoff and Benzon, 1989). This new technology is revolutionising the way data are being viewed and interpreted in such diverse fields as medicine, psychology, mathematics, geosciences, astrophysics, engineering, art, architecture, communication, and entertainment (Friedhoff and Benzon, 1989; McCormick et al., 1987). Geographers are also embracing visualisation, often coupling it with geographic information systems (GIS), to produce high-tech graphics for spatial problem solving in what is called "geographic visualisation".