What in the World is This?

Decoding the semiotics of maps

Let’s start by laying the foundation. What are “semiotics”? And what is the purpose of a map?

The study of signs is called semiotics. This is essentially decoding the meaning and message behind visual designs — maps in the case of this blog post.

“A photograph shows all objects in its view; a map is an abstraction of reality. The cartographer selects only the information that is essential to fulfill the purpose of the map, and that is suitable for its scale. Maps use symbols such as points, lines, area patterns and colors to convey information.” (Wilford, n.d.) Therefore, the goal of a map is to simplify the Earth’s surface to a few attributes so that a make a viewer can visually distinguish and then interpret a key message.

Map of the Average Employment Income, City of Toronto, 1980

Map 1. (Source: Centre for Urban Studies and Communities, University of Toronto, n.d.)

The busy array of colours and patterns in the map displayed above can make it difficult for the viewer to decode the message. So, what exactly is this map trying to convey, and how can the visual design be improved?

The map visualizes employment income of the Toronto Census Metropolitan Area (CMA) in relation to highways and the TTC subway network. However, one might be lead to believe that this map is displaying more than 1 variable, due to the variety of colours and patterns chosen to symbolize each income class. Moreover, the map does not outright state the average employment income for the Toronto CMA. The income brackets are formatted in terms of percentage more than the CMA average. What type of average — arithmetic, geometric or harmonic?

According to cartographic standards, income data is supposed to be represented by a yellow-brown colour range (see map 2), where the lightest shade (yellow in this case) is the lowest value and the darkest (brown) is the highest. This makes it simpler to distinguish which area falls into a high or low category.

Map 2. (Source: Local News Research Project by Christina Wong, 2012.)

Geographic areas without data or that are classified as non-residential areas ought to be represented in grey rather than a pattern with a white background. White with patterns is usually reserved for a map this is entirely in grayscale. (See map 3 below for a grayscale example.)

Map 3. (Source: John Krygier, 2007.)

Overall, the visual design of Map 1: Average Employment Income, City of Toronto, 1980 could be improved in order to make the message easier for the viewer to take away.