How to make an Apple Tart? Part 2

The art of cartography in 7 steps, continued and finished.

In the first part, I introduced how to properly prepare all the ingredients necessary for making a delicious Apple Map.

Part 2: Maps with flavor.

We continue the recipe with my favorite subject: presentation. From choosing colors to creating the legend, how do you make a map accessible and quickly readable?

1. Season with colors.

Ensure readability.

I can't say it enough, readability is paramount! What's the point of making maps if no one can understand their content? And when it comes to map colors, the major aspect to play with is contrast.

Color has two major qualities: its strong differential power, which comes from the human eye's ability to recognize a very wide diversity of hues, and its great aesthetic value.

Béguin M., Pumain D. (2005). The representation of geographic data. Armand Colin.

For maps intended for printing, as is the case for city maps and Breton coast posters by Cartes aux pommes, the primary colors are cyan, magenta, and yellow, with black added. This is called CMYK printing. Colors are obtained through combinations of the three primary colors and black. These combinations provide a vast, very vast palette of hues whose composition is measured in percentages.

This orange hue is obtained by superimposing 0% cyan, 30% magenta, 50% yellow, and 0% black.

When the printing quality is good, it can be considered that a minimum of 20% difference in value between two tones (e.g., a light green and a darker green) is needed for them to be easily distinguishable. To be sure and avoid any ambiguity, I prioritize a difference of 30, or even 40%, when working on the color range of maps.

The secret ingredient: graphic semiology

Graphic semiology is the language that allows for the graphic translation of information. Color is one of the visual variables used in this language to separate cartographic elements of different natures.

It is the visual variable that most effectively conveys qualitative information. All major inventory maps (geological, pedological, climatic, land use maps, etc.) extensively use color.

Béguin M., Pumain D. (2005). The representation of geographic data. Armand Colin.

It is this (more or less) universal language that allows you to quickly grasp the information on a base map. Colors are not chosen randomly but according to their ability to convey precise information. For example, green is often used to represent natural spaces, while blue is more likely to be used for hydrographic elements.

Example of the color range chosen for the city map of Lyon.

The idea is to use evocative colors, i.e., colors that are both quickly perceptible and identifiable due to the habit created by these conventions. These colors allow for significant time savings in reading the map.

Depending on the subject of the map, we can more or less have fun breaking free from these conventions.

Thanks to graphic semiology, the map becomes a visual language, capable of telling a story at a glance.

2. Bake with a flavorful legend.

For each map, a little mental gymnastics is necessary to ensure a good understanding of the information via the legend. It must be clear and simple.

It is an essential element for understanding many maps, but some maps can do without it.

Because you have always been more or less exposed to maps of the Breton coast, for example, you can determine where the cities, beaches, and sea are.

On this type of map, an appropriate color choice allows for omitting a legend.

Conversely, for city maps, a small explanation may seem wise. And for the legend to be easily understandable and applicable to the map, it should be quickly readable and comprehensible.

The smaller the map format, the less information can be placed on the map background. This variation must also be reflected in the legend.

Comparison of the legends of the Bordeaux city map, 30 x 40 cm format (left) and A4 format (right).

You have to put yourself in the reader's shoes and step back enough from your work to find the right terms and design that will resonate. It's a fun little brain-twisting exercise that I enjoy doing.

3. Adapt the recipe for all tastes.

Each city map is available in different formats to meet everyone's interior decoration constraints.

To ensure readability (yes, I know, again), it is necessary to adapt the amount of information on the map background to the poster's printed format. The larger the map format, the more detailed the map. The largest format offered in the shop is the Gourmand format of 50 x 70 cm. This is the easiest large format to frame. Beyond that, there are fewer choices in materials, colors... unless you hire a professional framer, which is not the same budget.

The Rennes city map in Gourmand format, framed.

In this format, the legend details the distribution of land-use types. This is the same level of detail as when I download the OpenStreetMap database, meaning the finest. Given the format, I was able to add the names of the largest spaces, main streets, and secondary streets.

The Goûter format (30 x 40 cm) will offer the same level of detail in the legend as the Gourmand format, but by playing with the superposition of information layers, I will be able to simplify and adapt the message's readability to this format. For example, the layer on which the smallest piece of grass is drawn will be visible on the Gourmand format but will not appear in residential areas on the Goûter format so as not to interfere with the overall reading.

Comparison of the grassy areas on the Rennes city map in Gourmand format (left) and Goûter format (right).

This smaller format will also not allow for retaining all the typographical information of the Gourmand format. Therefore, there will be less detail in place names and street names.

Finally, the Encas format, which corresponds to an A4, is a simplified version of the two larger ones. The legend is much less detailed and corresponds to groupings of information.

The Saint-Malo city map in Goûter and Encas formats.

The reduction in format and the minimum font size required for readability only allows for keeping the names of the largest spaces as reference points.

Regarding the maps of the Breton coast, the goal is to represent your favorite part of the coast in as much detail as possible. Therefore, it is the area's size that will determine the map's format.

As with city maps, I have chosen a maximum format of 50 x 70 cm, which will allow you to easily find a frame for your map, whatever the material and price that suits you.

Attention to detail.

Although computing is fantastic, not all bridges between software are simple and foolproof. The consistency of information must always be checked. For typeface readability, human intervention remains essential, because a rule valid for one geolocated point is not necessarily valid for its neighbor.

On average, I need 30 hours of work to create a map. Once the creation is complete, I hand it over to Sel de Pixel, a digital photo lab in Rennes, for printing. This step will add the final touch to the map, and it is thanks to their professionalism that I can offer you maps with vibrant colors for lasting memories.

Want to see what it looks like for your favorite spot? It's right here!