Transcription
Howdy! It's Kyle, talking about map projections because we live on one of these, and we like to look at flat maps. There's no way to display the near-spherical nature of the Earth onto a flat piece of paper without making major compromises, and that's what a map projection is. You may have seen a demonstration where a scientist tried to peel an orange and then flatten out the peel onto a table, and of course, you can't do it. And that's what a map projection is: trying to get that peel to look as good as possible when flattened out.
So, in this video, I'm going to take a look at all kinds of different map projections, what they're used for, what might be the best or worst ones to get one of these onto one of those. I'm going to first go over map projections in general, and then discuss specific projections after that. For dimensions, a map can compromise the shape, size, or the relative location, or it can be an interrupted map. Some maps can perfectly preserve one major aspect, such as an equal-area map, equidistant, or conformal, and I'll get into each of those later on. But if it preserves one aspect perfectly, then the other ones have to be compromised even greater. So if you want to keep the shapes of the landforms looking correctly, the sizes are going to be way off. Or if you want the areas to be equal, the shape is going to be off. Or a map cannot preserve any one aspect perfectly but make small compromises to all of them. So essentially, a map projection is a cartographer's take on those compromises, and it's all based on math and geometry, and they can get pretty complicated as well. I'm not going to get into the math of it all because I can't. But because it is math, there are essentially an infinite number of map projections possible for getting the actual image onto a piece of paper. The three major methods are cylindrical, conical, and planar.
For a cylindrical projection, imagine a piece of paper being wrapped around the globe like a cylinder. With light, the map is projected, but as it's rolled out, you can see how the polar areas are going to be stretched. And there's not one type of cylindrical projection; there are many that are based off of this. So by messing around with the math, you can make the maps look a lot different, even though you're still using a cylindrical projection. For a conical map, imagine placing a cone-shaped piece of paper on the globe like a hat. The shape of the conical map itself can be kind of strange if it's trying to show the entire world. It is worth noting that there are more types of projections than just cylindrical and conical, and even within cylindrical, there are different types of ways of doing the cylinder, and within conical, there are different ways of doing the cone. You also have planar projections, which follow azimuths, as well as polyhedron type projections that do a pretty good job of preserving shape and area, but they look really weird. But for the sake of this video, I'm going to talk about primarily the cylindrical and conical.
So now let's talk about some of the individual projections. First, I want to discuss conformal projections. These are ones that preserve the proper shape of what's being shown on the map at great compromise to size. So I want to start off with talking about everyone's favorite projection: the Mercator. This is a very old projection, created in the mid-1500s, and it was used primarily for navigation on the seas. Some of the benefits of the Mercator is that all the lines of latitude and longitude intersect at 90-degree angles, as well as North is always up and South is always down. But the obvious compromise with the Mercator Projection is size. The polar areas are greatly stretched out and can actually look kind of comical. It usually cuts off the most Arctic and Antarctic parts of the map. So if you were to see an entire Mercator Projection, the Arctic areas and Antarctic areas look even more ridiculous. But as being primarily a projection used for sea navigation, there wasn't a whole lot of navigation in the Arctic and Antarctic areas at the time. So the mid-latitude areas are preserved pretty well. But nonetheless, the Mercator Projection is responsible for why so many people think Arctic areas are much larger than they really are.
So I'm going to show you just how much Mercator Projection distorts size by using this website, True Size Of. It's a great website to mess around with, and I'll leave a link to it in the description so you can take a large landform from a higher latitude area like Russia or Greenland or Canada and superimpose it on an area in the mid-latitudes to see where this relative size actually is. So a Mercator Projection is not a great one to show the entire globe, but it is great for showing much localized areas. Maps like this are usually not very good at the small scale but are much better at large scale. So many of the applications that we use with maps, to the larger scale to show a smaller area, are often shown in Universal Transverse Mercator, and that's just a transversely oriented Mercator Projection but zoomed into a much larger scale. And I didn't mention this before, but a large-scale map shows smaller areas. So a small-scale map is used for a globe or large continental regions. A large-scale map shows small areas, and this is the map projection used by Google Maps and most other map services. And with Mercator, North is always up, South is always down, so that makes for a very good local navigation directions.
So the Mercator Projection is by far the most well-known one of the conformal shape projections, but it isn't the only one that is conformal to shape. Another one in this category is the Lambert's Conformal Conic Projection. This one is often used for aviation navigation because a straight line on a map is pretty close to a great circle on a globe. So this isn't one for most people's day-to-day use, but it is an important one in terms of aviation and again, following great circles. Here's another one that conforms to shape; it's called the Adams Hemisphere and a Square Projection. And well, it's a hemisphere and a square. This is an example of a projection that doesn't really have any practical uses but looks kind of cool, I guess. But much like a Mercator, the areas in the polar regions are distorted and look much larger.
The next type of projection I'm going to discuss are the equal-area ones. As the name implies, the area of things shown on a map is perfectly preserved, but scale and shape are distorted. So to give you one of the more extreme examples of an equal-area map is the Collignon Projection. So on the equal-area map, each of the landforms shown on here has its proper area, but as you can tell, the shapes are way off. This particular projection has uses in astrophysics but not really much else. Another equal-area projection is the Sinusoidal. This looks a little bit more like a normal map, but as you can see, it is still very distorted in terms of its shape to preserve area. But what defines this projection is the fact that the poles are points, and therefore you get a more accurate representation of the size of the polar regions in relation to the rest of the Earth. The Bonne Projection is one of the many that has kind of a heart shape to it. So for this Bonne Projection, it looks kind of strange at the global scale but is used quite often at a more large scale to show smaller local areas. Another one of the heart-shaped projections is the Werner Projection, and again, these heart-shaped projections are often used at the larger scale to show more localized areas.
One that many of you might be quite familiar with is the Albers Projection. For example, if you're familiar with the U.S. Geological Survey Topo quads, they use the Albers Projection on those, and this is also the projection that the U.S. Census Bureau uses for mapping. One of the most recent projections to be created is the Equal Earth Projection, and you very well may have seen this projection used. This has been adopted by many agencies worldwide. In terms of global projections, I always preferred the ones that have the curved sides, like this one, or the Robinson Projection that I will discuss later on.
The next equal-area one I want to discuss is the Gall-Peters Projection. This one is sometimes referred to as the anti-Mercator because the Mercator stretches out the polar areas to a great extent, and this projection stretches out the tropical areas to a great extent. So, as with all equal-area projections, there has to be a big compromise in terms of shape. Many people think that this projection was created recently to kind of offset the Mercator; however, it was created in 1885, so this goes back quite a ways. You'll sometimes hear some debates over which one's better, the Mercator or the Gall-Peters. Can we just say they both suck?
The third major type of projection I want to discuss are equidistant ones, and as it sounds, it preserves the distance from one point to all other points on a globe. The Equidistant Conic Projection is one of these, and it is very lightly used but is normally just used for small countries showing large-scale small areas. And just like all conic projections, it's much better to show things that are oriented East-West as opposed to North-South. So a great map for Tennessee, not so much for Chile. Another one that is equidistant is called the Equirectangular Projection, and as the name applies, every rectangle on the map is equal sized. It does some of the properties of a Mercator but does not have conformal shape and is also not equal area. So as a result, it doesn't really have any practical uses and is often just used for thematic reasons.
Another type of projection is a Gnomonic Projection. The primary feature of this projection is that all great circles on the map are displayed as straight lines, and as a result, a straight line on this map is the shortest distance between two points. Some map projections can actually be composite projections, whereas a combination of two other ones. The best example of this is the Goode Homolosine Projection. When you see a map presented like this, it's referred to as interrupted, and sometimes you'll hear about a projection like this referred to as an orange peel projection. So the benefits of this one is a lack of distortion in terms of shape, size, or distance, with the obvious compromise here being aesthetics and the map being interrupted. This is an equal-area map, so each of the landforms shown on here are the proper size, and because of the interrupted nature of it, the shape of the landforms is less distorted than some others.
And the last general type of map projection I want to discuss are the compromise ones. These are ones that do not preserve any dimension, so they're not equal area, conformal shape, or equidistant. The idea is to compromise each of the dimensions a little bit to get a more well-rounded map. Perhaps the most well-known of the compromise projections is the Robinson. And so there are many benefits of this, including the curved sides, meaning the polar areas are not stretched out as much, but there is still some distortion, as you have to compromise a little bit of everything. For a while, this was the standard map projection of the National Geographic Society, and I've always felt that the Robinson and the ones very similar to it are the overall best-looking maps showing the globe.
Another popular projection in the same general vein as the Robinson is the Winkel Tripel. So lots of math to get this projection, and in 1998, the National Geographic Society switched from using Robinson as their official projection to the Winkel Tripel. But not all compromise maps are aesthetically pleasing. One is the Buckminster Fuller Dymaxion Map. So obviously, when you see this, you're thinking, what on Earth, literally, is this? And even though this map is neither equal area nor conformal shape, it does compromise those two very little. But of course, the big compromises are distance and appearance.
One of the more interesting compromise projections is called the Armadillo. So as you can see, it shows about three-fourths of the globe and has almost a 3D feel to it. So more than most other projections, this shows the near-spherical shape of the Earth. And one nice thing about this projection is that it doesn't leave anything off the map. And the last individual projection I wanted to show is the Nicolosi Globular Projection. This is referred to as a polyconic projection; multiple cones are placed on the globe, but this projection can only show one hemisphere at a time. So when it shows the entire globe, it's usually like this, kind of like a pair of glasses. So like many compromised maps, it doesn't have a hard practical use, but it is very aesthetically pleasing.
It's hard to say which of these projections are the best and worst because many of them have a very specific use, others are meant to be a little more artistic, or are meant to look weird. But in terms of just general use of a map, like doing a Google image search, trying to find a map of the globe that shows whatever, I like to think we'd get away from using them, like Mercator and Gall-Peters style perfectly rectangular maps, and move more towards the Robinson and Winkel, Equal Earth style maps that have the rounded sides. I think those are just much better in terms of the overall aesthetic appearance, but also give a more accurate representation of what you're actually seeing on the Earth.
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