Maps 101 : Projections, from 3D to 2D

4 min readOct 30, 2023

How do we take this 3D planet and make it 2D for everyday use ?

This is part #2 of an ongoing series where we delve into the technical aspects of cartography, real-world case studies of its utility and insights into the industry. Subscribe and Join us for the ride! At the end, you’ll be as enthusiastic about maps as we are.

Sir John Murray’s map of the Indian Ocean accompanying the Summary of Results of the Challenger Expedition, 1895. Source: Photo by NOAA on Unsplash

Part 1: Map Projections

What are Maps and What is Cartography?

A map can be understood as a visual representation of an area, showcasing details such as geographic features, roads, cities, and more. Cartography is the map-making process. It is a fascinating blend of art, science, and technology to representation of spatial information in a way that is both accurate and comprehensible to users.

The boundaries of map-making are expanding further with the emergence of 3D, augmented reality, and even mapping satellites in space.

Image showing mapping of Satellites in Space.

Map Projections

Since the Earth’s vastness is challenging to capture perfectly on paper or screen, cartographers have developed “projection.” Projection refers to translating the Earth’s three-dimensional, curved surface onto a flat, two-dimensional surface (like a map or a screen).

All map projections involve a degree of distortion, be it in area, shape, distance, or direction. If you want to know what the world REALLY looks like, with no distortions at all, you really need a globe. (Not really though; even a globe is off; the real shape of the world is actually called a Geoid)

The actual shape of the earth (Source: NOAA)

Projection properties

We talk about map projections in terms of the ways in which they distort or preserve certain things about the Earth. We call these projection properties. There are three main properties: Area (Some projections distort areas), Form (Some projections distort the “form” of features), Distance (Most projections distort distances)

The type of projection you choose is dependent on what aspects you prioritize: angles, area, distance or direction. To preserve angles, a conformal projection is best. To preserve area, you use an equal-area projection. To preserve lengths/distances, the category is called equidistant projection

With conformal projections, most small shapes on the map will appear in the same shape as they do on the Earth’s surface.

Mercator projection excels in preserving angles for navigation but it does make land near the poles (like Greenland) look much larger than it really is. Source; Tobias Jung

If you’re studying the true shapes of lakes or national boundaries in your region, the Lambert Conformal Conic is invaluable. Source; Tobias Jung

Equal area projections preserve area. Area is an all or nothing property. A map projection either preserves areas everywhere, or distorts it everywhere. Shapes, angles, and distances might be distorted, but the representation of area remains constant.

Albers Equal Area Conic Projection aims to represent true areas, making it ideal for understanding real-world sizes, such as comparing the size of forests or countries. Source; Tobias Jung

Mollweide Projection is particularly useful for global datasets like temperature or population distribution. Source; Tobias Jung

Equidistant Projections preserve distance from some standard point or line. They maintain true scale between a specific location and every other place on the map.

The Azimuthal Equidistant Projection portrays distances accurately from the center point to any other point on the map and especially valuable for applications such as radio and seismic mapping. Source; Tobias Jung

Significance of Map Projections

Understanding map projections is vital because they influence our perception of the world. Just as photo filters can change how we see a scene, different map projections can subtly shift our understanding of geography, power, and significance.

The Gall-Peters projection is a cylindrical equal-area projection. This means that it represents areas correctly at the expense of shapes, particularly as you move towards the poles. Source; Tobias Jung

The Gall-Peters projection seeks fairness by showing countries in their true size. This means nations, no matter where they are located, appear in correct proportion to one another. Yet, this comes at a cost as some landmasses might seem a bit stretched or oddly shaped.

Comparison Silhouette map showing the Gall Peter’s Map Projection in Red and the Mercator Projection in Cyan. Source; Tobias Jung This is a reminder that maps, like stories, have perspectives, and it’s essential to understand what’s being emphasized and what might be getting compromised.

The Gall-Peters projection has gained both support and criticism: supporters appreciate its accurate area representation, especially for countries near the equator, suggesting it offers a more equitable view of the world. Critics, however, point out its distortion of country shapes and note other projections can achieve similar goals without such distortion.

Map projections might seem like a topic reserved for geographers or history buffs. Yet the way we perceive our planet affects our understanding of global issues, travel, culture, and even politics. Consider this: you wouldn’t want to rely on a distorted mirror image to choose an outfit, so why would you rely on a distorted map to understand the world?

On a lighter note…