Maps… They can be very simple or almost a work of art. We use them in our phones for sightseeing, in sat navs for directions, and the “old school” paper way when hiking. They can describe the terrain we explore, the distribution of natural phenomena, the history of human civilisation, war campaigns, geology, geopolitics, biodiversity distribution, population, and socio-economics (see 34 unusual maps). This list could go on. They are one of the most fundamental ways we use to describe the world (and learn about where we are!).
At the end of 2016, a graduate of Tokyo Keio University, Hajime Narukawa, won the coveted Grand Award at Japan’s ‘Good Design Awards’ (beating over 1000 other entries, from robotics to wheelchairs, apartment buildings to parks) by submitting a map (Figure 1). This map is close to perfection when it comes to proportion, and it can be folded in to a globe.
So why is a simple map so important that it could win a prestigious award? Well in short, maps are quite inaccurate, and the reason behind this is quite simple. Have you ever tried to peel an orange and then use the skin to create a flat surface? It’s not that easy as the skin very quickly begins to crack and tear. This is why it is so hard to transform a sphere into a 2D surface. There are over 50 ways to project a map, each of them compromises somewhere to avoid “the cracks”. They can, however, be grouped by the type of surface they are trying to project. Here are some of the most common ones (Figure 2):
- Cylindrical – Here the surface is “wrapped” around the sphere. It maps meridians and circles of latitude (parallels) as evenly spaced vertical and horizontal lines.
- Conic – Created by fitting a cone shape over the sphere. In this projection meridians are represented as straight lines, and parallels as arcs of circles.
- Azimuthal, or planar – This projection has meridians represented as straight lines and parallels as concentric, symmetrical circles. This map has a central point at which circles running through it are represented as straight lines.
The additional variations comes from the different application of aspect (the orientation of the surface in relation to the sphere, e.g. polar, equatorial), case (how the surface touches the sphere, e.g. tangent, secant), and perspective (the location of the light source for the projection, e.g. gnomonic, orthographic, or stereographic).All of these transformations aim to preserve a specific reality while distorting others. For example, by conserving local shapes (conformal properties), the distances between points (equidistant), the direction (azimuthal), or conserving specific areas – but compromising some of the properties. Finally, there are projections that aim to reach a compromise between all of the four properties.
OK, OK, I know I have bored you with map properties and I can hear you cry, “I don’t care that much about maps”, “it doesn’t really matter, does it?”. To answer this let’s go through three common map projections and look at them in detail, starting with the most commonly used Mercator.
It was designed in 1569 for navigation purposes. It is a cylindrical and conformal projection. One of the biggest problems with it, is that it cannot show the Poles, as the areas are exaggerated with latitude. This also means that Greenland appears to be larger than Africa. Many have argued that this map promotes the North American- and European- centric view of the world, because these areas appear much larger than they really are.
On the other hand, Gall-Peters is a cylindrical and equal-area projection that people say is superior to the Mercartor map. I think those of you with a bit of aesthetics flair will agree it is quite ugly. They have managed to keep the size of the regions (within 45° N and S) accurate, but areas are stretched horizontally near the poles and vertically close to the Equator. So shape becomes a big problem!
The third projection is Winkel triplel (Winkel III), adopted by National Geographic. So it must be good, you think… not so! This pseudo-azimuthal, compromise projection was designed to minimise distortion in all three properties: areas, direction and distance. It does a pretty good job, but the areas near the Poles are still distorted. Also, as angles are not preserved, this map will never make it in navigation “circles”.
Still not convinced that this all matters? What if I said that maps can really affect how people view the world, as summed up in this clip from a great little show called “The West Wing” (for those of you too young to remember it, do yourself a favour and watch at least 2 seasons).
The conclusion? All maps distort reality! Every single one (though we are getting closer with the new Japanese map shown above)! However you can choose the most suitable projection depending on the purpose of the map.
Or just #BringBackTheGlobe!
Some information on how distortion is scored
More map projections