Why all world maps are wrong

Why all world maps are wrong

Why all world maps are wrong

Making accurate world maps is mathematically impossible.
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Maps are flat representations of our spherical planet. Johnny Harris cut open a plastic globe to understand just what it takes to turn a sphere into something flat.

His struggle to make a flat map out of the plastic globe is indicative of a challenge mapmakers have faced for centuries: It is mathematically impossible to translate the surface of a sphere onto a plane without some form of distortion.

To solve this problem, mathematicians and cartographers have developed a huge library of representations of the globe, each distorting a certain attribute and preserving others.

For instance, the Mercator projection preserves the shape of countries while distorting the size, especially near the north and south pole.

For a more accurate view of land area look at the Gall-Peters projection, which preserves area while distorting shape.

In the end, there’s not “right” map projection. Each comes with trade-offs, and cartographers make projection decisions based on the particular tasks at hand. But if you are interested in seeing an accurate depiction of the planet, it’s best to stick with a globe.

Interact with projections: http://metrocosm.com/compare-map-proj…
Mercator tool: http://thetruesize.com/
Mike Bostock Map Transitions: http://bl.ocks.org/mbostock/3711652
Mercator Puzzle: http://hive.sewanee.edu/ldale/maps/10…

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Content

4.64 -> If I want to turn this globe into a flat map,
7.68 -> I’m going to have to cut it open.
17.08 -> In order to get this to look anything like a rectangle.
21.56 -> I've had to cut it in places. I've had to stretch it so that the countries look all wonky.
27.72 -> And even still, it's almost impossible to get it to lie flat.
34.34 -> And that right there is the eternal dilemma of map makers: The surface of a sphere cannot
39.69 -> be represented as a plane without some form of distortion.
43.17 -> This guy proved that with math a long time ago.
46.239 -> Since around 1500s, mathematicians have set about creating algorithms that would translate
51.019 -> the globe into something flat.
52.96 -> To do this, they use a process called projection.
56.53 -> Popular rectangular maps use a cylindrical projections.
59.42 -> Imagine putting a theoretical cylinder over the globe and projecting each point of the
63.949 -> sphere onto the cylinder’s surface.
67.36 -> Unroll the cylinder, and you have a flat, rectangular map.
70.75 -> But you could also project the globe onto other objects, and how exactly a map maker
75.57 -> projects the globe will affect what the map looks like once it’s all flattened out.
80.21 -> And here’s the big problem: Every one of these projections comes with trade offs in
85.81 -> shape, distance, direction and land area.
88.52 -> Certain map projections can be either misleading or very helpful depending on what you are
93.221 -> using them for.
94.28 -> Here’s an example.
95.67 -> This map is called the Mercator projection.
98.13 -> If you’re American, you probably studied it in school.
101.31 -> It’s the projection Google Maps uses.
103.86 -> Mercator projection is popular for a couple of reasons.
106.28 -> First, it generally preserves the shape of the countries.
109.19 -> Brazil on the globe has the same shape as Brazil on the Mercator projection.
113.57 -> But the real purpose of the Mercator projection was navigation -- it preserves direction,
119.72 -> which is a big deal if you are trying to navigate the ocean with only a compass.
123.42 -> It was designed so that a line drawn between two points on the map would provide the exact
127.98 -> angle to follow on a compass to travel between those points.
132.39 -> If we go back into a globe, you can see that this line is not shortest route.
135.97 -> But it provides a simple, reliable way to navigate across oceans.
140.51 -> Gerardus Mercator, who created the projection in the 16th century, was able to preserve
144.89 -> direction by varying the distance between latitude lines while also making them straight,
150.12 -> creating a grid of right angles..
152.79 -> But that created other problems.
154.54 -> Where mercator fails is its representation of size.
157.67 -> Look at the size of Africa as compared to Greenland.
159.92 -> On the mercator map they look about the same size.
162.51 -> But look at a globe for Greenland’s true size, and you’ll see it’s way smaller
167.1 -> than Africa.
168.1 -> By a factor of 14 in fact.
171.95 -> If we put some dot that are all the same size on a globe, then we projected as a mercator
176.85 -> map, we would end up with this.
179.18 -> The circles retain their shape but are enlarged the closer you get the poles.
184.43 -> One modern critique is that this distortion perpetuates imperialist attitudes of European
189.23 -> domination over the southern hemisphere
191.51 -> "The Mercator projection has fostered imperialist attitudes for centuries
196.08 -> and created a ethnic bias against the third world."
198.94 -> "Really?"
199.84 -> If you want to see a map that more accurately displays size, you can use the Gall-Peters
205.54 -> projection, which is called an equal-area map.
207.84 -> Look at Greenland and Africa.
209.819 -> The size comparison is now accurate.
211.39 -> Much better than the mercator.
212.89 -> but it’s obvious that the country shapes are now stretched.
216.88 -> Here are the dots again so you can see how the projection preserves area
221.16 -> while totally distorting shape.
225.34 -> Something happened in the late 60s that would change the whole purpose of mapping and the
229.349 -> way we think about projections.
231.06 -> Satellites orbiting our planet started sending location and navigation data to little receiver
236.09 -> units all over the world.
252.95 -> This global positioning system wiped out the need for paper maps as a means of navigating
257.56 -> both the seas and the sky.
259.489 -> Map projection choices became less about navigational imperatives and more about aesthetics, design,
264.94 -> and presentation.
266.36 -> The mercator map, that vital tool of pre-GPS navigation, was shunned by cartographers who
272.59 -> now saw it as misleading.
274.34 -> But most web mapping tools like Google maps still use the mercator.
278.36 -> According to Google this is because the Mercator’s ability to preserve shape and angles makes
282.69 -> close-up views of cities more accurate -- a 90 degree left turn on the map is a 90degree
287.69 -> left turn on the street you’re driving down.
290.18 -> But when trying to display something on a world map, cartographers rarely use the mercator.
297.62 -> Most modern cartographers have settled on a variety of non-rectangular projections that
301.639 -> split the difference between totally distorting either size or shape.
305.38 -> In 1998 The National Geographic Society adopted The Winkel tripel projection because of it’s
310 -> a pleasant balance between size and shape accuracy.
312.83 -> But the fact remains, that there is no one right projection.
316.43 -> cartographers and mathematicians have created a huge library of available projections, each
321.58 -> a new perspective on the planet.
323.96 -> The best way to see what the earth really looks like is to look at a globe.
327.99 -> But as long we use flat maps, we will deal with the tradeoffs of projections, Just remember:
333.26 -> there’s no right answer.

Source: https://www.youtube.com/watch?v=kIID5FDi2JQ