Episode 4: when size takes precedence over shape.

Two rooms, two atmospheres.

From the projection family, I would like… equivalent projections! This is the slightly more scientific name for our Surfaces team, which we discussed in this article.
Unlike conformal projections, which tend to preserve the shape of countries and continents, equivalent projections aim to preserve relative areas, meaning the same size ratio between one region and another.

Visualization of cartographic deformations with Tissot's indicatrix, on the left an equivalent projection and on the right a conformal projection (after Sting - CC BY-SA)

Some team leaders.

In this team, there are several names that might sound familiar.
For example, the Peters projection or the Gall-Peters cylindrical equal-area projection, in its long version. This projection is notably known for restoring continents to their actual size importance, as opposed to the Mercator projection.

Gall-Peters equal-area projection, from the NASA Earth Observatory's "Blue Marble" series.

For fans of the show Le Dessous des cartes on Arte, the Eckert IV pseudo-cylindrical equal-area projection might ring a bell. IV, because Max Eckert-Greifendorff was particularly productive in designing cartographic projections.

Eckert IV pseudo-cylindrical equal-area projection (Strebe - CC BY-SA)

This projection has the good taste of having been designed not only to respect areas but also to minimize distortions across the entire globe.
It's called pseudo-cylindrical because on this map, meridians are curved and parallels are straight. The meridians are curved precisely to reduce surface distortions that cylindrical projections can cause, as we saw in this article with the Mercator projection.

Adapting projections to your needs.

Just as conformal projections alter areas as you move away from the projection center, equivalent projections will tend to distort the shape of countries and continents.

Bottomley pseudo-conical equal-area map projection (Strebe - CC BY-SA)

This is why equivalent projections are generally not used to draw maps of countries, regions, or even cities. This type of projection will be found more in world atlases or those focused on a continent, for example, to respect the relative areas of different countries.

It's time to move on to the "I'm going to try something!" projection team! To learn all about this last family, it's here.