
143
9
Thematic Visualization
Introduction
Thematic cartography at its most basic is simply the graphic symbolization
of spatial datasets concerning a particular theme over a base map. There
are numerous types of thematic representations, or map styles, that can be
used for spatial visualization (e.g., choropleth, dot, proportional symbol).
Regardless of which form of representation is employed, all thematic maps
are created by manipulating visual variables.
As noted in Chapter 7, most visual variables are only ideal for represent-
ing certain types of data. Thus, one of the rst things to remember is that
not all thematic representations are suitab ...