Production graphics environments (e.g., Photoshop, Freehand) offer the most comprehensive set of tools to make attractive graphics, but are limited to two dimensions. More important, their content is not directly addressable (i.e., the image produced does not consist of individual features that can be selected and manipulated at will).
Animation environments (e.g., Director, Flash) are becoming popular as a means to bring interactive, animated graphics into a web environment (usually via the web plug-in). Analytically, they are limited and they are time-consuming to use. Nonetheless, they can produce effective, specialized teaching and learning aids that deal directly with time, thus allowing descriptions of processes to be animated, and they allow unimportant interface details to be hidden from the end user. Examples of Flash applications for K–12 education are available on the web from http://www.geovista.psu.edu/grants/MapStatsKids/pubs.html.
Visual Exploration Systems
Information visualization systems (e.g., Data Explorer [DX], Advanced Visualization System [AVS]) can sustain the greatest variety of data types. They provide support for the third dimension and often for time as well. They permit a high degree of flexibility in the way that data are displayed. However, they offer limited analysis capability. In information visualization systems, spatial variables have no special status and no predefined assignment because any data value can be assigned to any visual variable. Thus, whereas in a GIS only data that are specifically spatial can be used as the location of an object, information visualization systems enable users to assign any data to be represented by, say, location or height.
Concept mapping tools (e.g., TouchGraph, ThemeRiver) spatialize data that are not inherently spatial, relying typically on an algorithm to order the position and displacements between components of the display (Figures 2.4 and 2.5). Like information visualization methods, concept graphing tools are usually geared toward visual exploration rather than analysis. They do not address any of the explicitly geographical aspects of spatial information.