The Cartographic Language
Feb 26, 2025
Cartography is the discipline aimed at making maps.
Cartography has scientific, technical, and artistic foundations.
Mathematics is one of the pillars of cartography: geodetic systems, coordinate reference systems are fundamental tools for map making.
The preparation of maps (data management and transformations) is a process that requires precision and accuracy .
The cartographic process is based on a set of rules from the semiology of graphics and on strong methodological tools.
The map itself is the subject of numerous researches: communication efficiency, animated cartography, optimization of flow mapping…
Cartography is based on the acquisition, preparation and processing of data. It requires the use of specialized software products (spreadsheets, GIS, mapping software, spatial databases…).
The process of map creation usually involves a search for aesthetics, design, and a certain viewpoint on spatial phenomena.
As with any communication object, the graphic design of a map has an impact on the transmission of the message.
The context of production is important.
To better understand the issues of legibility and communication of the cartographic message, ask yourself
This directly influences the *geographic bounding box** and *projection** used, the *generalization** of the map background, the *graphic choices** (fonts, colors, format), the *vocabulary** used.
A widely appreciated tool for analysis, decision support and communication.
It is necessary to identify the graphical means that allow to go from a “simple” spatialized statistical information to an efficient graphical representation.
The message to be conveyed. The message should be coherent, clear, understandable and as simple as possible so that it can be easily integrated.
A map should be attractive. It should be aesthetically pleasing and well designed.
The map should be designed for a specific purpose. The mapmaker needs to know whom he/she is addressing.
The map is a professional tool of the geographer. It is a scientific object that follows strict and precise rules, it must be as reproducible as possible and thus open to scientific discussion/dispute.
Jacques Bertin has developed a set of rules for the graphical representation of information.
3 types of relationships within data sets. Maps are created to visualise these relationships.
6 visual variables to transcribe these relationships.
Differentiation: express relationships of equivalence or difference, with no hierarchy or classification.
Order: express a hierarchy in the data.
Proportionality: express raw quantities.
A visual variable refers to the way in which graphical figures are made to vary in order to visually represent variations in statistical data.
Localization refers to the position of a place on Earth’s surface. It is a geographical notion.
Positioning refers to the graphic transcription of geographical objects on a map using points, lines, or polygons. Is is a cartographic concept.
ONLY one visual variable can be used to show absolute quantitative data: the size.
It is the only visulal variable that can express differences, hierarchy and above all proportionality.
(and qualitative ordinal data)
The choropleth map: A cartographic representation consisting of ordered coloured areas on a grid (e.g. administrative division).
Used with relative quantitative data and ordered qualitative data.
The statistical information in your spreadsheet is not always ready to be mapped.
The information may need to be converted, collated or reduced to make it understandable.
Relative quantitative data (rates, indices, etc.) always need to be synthesised, broken down into classes of values.
This process is often called discretization.
Codes & Conventions help contextualize the map.
Mandatory elements:
Most of the figures and slides are from:
Lambert, N., & Zanin, C. (2020). Practical Handbook of Thematic Cartography: Principles, Methods, and Applications (1st ed.). CRC Press.
https://doi.org/10.1201/9780429291968
The chapter Cartographie thématique et règles de la sémiologie graphique from the course Initiation aux SIG et à la cartographie thématique by Ronan Ysebaert, Maxime Guinepain, Nicolas Lambert, Flora Hayat and Hugues Pécout.
https://github.com/rysebaert/infogeo