Area-class maps depict phenomena or objects which are extensively distributed.
Imhof (1972, p. 115) distinguishes three types:
Several graphical display elements can be used for the distinction of areas of different characteristics. The possibilities for variation depend on the chosen pattern type. The most common patterns are dot grids, scattered figures, line screens and fill colours.
The following table shows an overview of the possible display elements and their variation possibilities.
Conceptual differences of individual areas are mostly represented by varying their brightness. Thereby, darker colours indicate higher importance and lighter colours lower importance. If there are no differences in the importance, big differences in brightness should be avoided.
According to the form of the area patterns the items presented in the following interaction should be respected.