Visual Variables for Mapmaking

Visual variables. From left to right: position, shape, size, hue, value, texture and orientation. Credit: Volaya

Mapmaking is practically a visualizing process for geospatial data. Interpretation of the data is highly intertwined with the availability of symbols. The symbols allow the reader to observe, react and interpret the individual objects or components of the visuals. In the two-dimensional space, the coordinate position will be represented by a point, line, or area symbol. Here are the visual variables to communicate the substance of your geospatial data.

1. Size

Size signals the dimensions of the symbol. Proportional symbols are representing the proportional value of the data. Size also indicates the level of importance. If the symbols are bigger in size, most likely it represents the bigger value, taking an example of population size. The proportional square, circle, and other geometric forms, including irregular shapes like cartograms are used to display the variations of data. Line thickness can also represent the amount of flow data.

From left to right: (1) Bubble map by E-spatial (2) Flow/Movement map by Anita Graser (3) Cartogram from Wikipedia

2. Shape

Shape is used to “(1) reveal similar elements, and therefore different elements and (2) to facilitate external identification through shape symbolization” (Bertin 1983, 95). Different shapes of symbols…