Card projections in the world: which is the best?

Card projections in the world: which is the best?

We examine the most common card projections in the world, how they work and which is the best

kia is usually described as the geek in our relationship. She is the one with a degree in computer science, she is the one with the editor's eye and she is the Star Trek fan, who describes herself as Seven of Nine ... What is apparently cool? A friend recently described her as "the one who sets the apostroph in rock 'n' roll".

That means I also have a few strands from Geek in me. I am a bit of a history nerd and can speak very extensively about photo lenses and filters. But above all I love cards.

One day, maybe when we can win the lottery and can afford a house with more than one bedroom, I will have a cartography room that is devoted to my dozens of Ordnance Surnance cards, my collection of outdated classroom cards with names such as Rhodesia and Betschuanaland (now Zimbabwe and Botswana) and my range of huge atlases and creaking globes.

I love how cards stimulate conversations. Even with a lonely map on a poor wall in our London apartment, I saw how people held, observed and asked curious questions like "Why is the equator not in the middle?". or "Why does Greenland look smaller?".

The answer is in the exciting topic of card projections. Let me go into it in more detail.

Why do we need card projections?

In a perfect world, the earth would always be represented as a ball (more precisely as a flattened sphäroid or ellipsoid). However, a globe is not practical. It cannot simply be worn, transported or kept in the pocket.

It is not suitable for large -scale use, e.g. B. to find directions in a city or to follow a hiking route where a more detailed picture is essential.

On a curved surface, measuring off -road properties is difficult, and it is not possible to see large parts of the earth at once. Globes also do not work well on our smartphones, tablets and computer screens.

Alt = "Tablet with mapping app"> Dream time Globen do not work well on flat screens

The problems above make the production of globes expensive, especially in different sizes and scales, and impractical for everyday use. Therefore we create cards.

whether paper form such as leaflet, booklet or atlas or digital formats embedded in websites and applications, we create two -dimensional projections of spherical earth.

What is a card projection?

In its simplest form, a map projection is the transmission of the curved earth's surface (or part of it) to a flat surface by using mathematical equations: making the three -dimensional two -dimensional - or making the curved world flat.

alt = "Maps-Changed-World-Bleau"> GuShefraver to make the curved world flat, the challenge of mapping

During such a transformation, width and length degrees are converted into Cartesian coordinates (X, Y) that represent the position of points on a flat card. There must be distortions - they cannot. Depending on the purpose of the card, some of these distortions are acceptable, others are not.

A card projection is classified depending on the type of mathematical formula that is used to project the spherical globe onto the flat card. Card projections protect some of the properties of the ball at the expense of others and create cards that seem to represent the world in different ways.

basic types of the card projection

The best way to describe how a card projection works is to imagine a piece of paper (the card) that is placed over the earth (or a globe) to get the width and length degree lines for the card.

Where the piece of paper touches the globe, there is no distortion on the menu; It is an exact image of the globe. Where the paper is not flat, there is a distortion. The further the paper is from the surface of the earth, the greater the distortions.

Alt = "How distortion on paper works"> ICSM: CC 3.0 Imagine a sheet of paper that is placed flat over the earth-this will be the card

Mathematics in various projections tries to overcome this problem - but none eliminates all distortions. On the whole, there are three basic techniques used to create a projection and thus a card.

azimutal: This piece of paper is laid flat and touches a globe at one point - usually a pole, but not always.

conical: The paper is rolled into a cone shape and touches a ball on a circular line. Typically, the tip of the cone is positioned over a rod.

cylindrical: The paper is rolled into a cylinder around the globe and touches the earth on a circular line - usually on the equator.

alt = “types of projections”> ICSM: CC 3.0 The three main types of card projection: Azimutal, conical and cylindrical (LR)

There are also pseudocylindrical. This is essentially the same as cylindrical, but with the progress in computer modeling it was possible to calculate the length of the length as curves and thereby reduce distortion near the poles. It is also my favorite variety.

Alt = "Card projection pseudo-cylindrical"> Strut: CC 2.0 Advances in the calculation of medium distortions near the poles are reduced in pseudocylindrical projections

joint card projections

azimutal stereography: The oldest form of card projection can be found until the 2nd century BC. Chr. Back. The oldest known recording of this projection comes from Ptolemy from 150 AD. The stereographic projection is the most common form of azimutal projection that is still used today.

The attraction of the projection is that the earth appears viewed as from space or a ball. The forms of the land mass are generally well preserved, although extreme distortions occur towards the edge of the card.

alt = “two globes”> Tobias Jung CC 4.0 looks like a ball, although extreme distortions occur towards the edge

Mercator: In 1569 Geradus Mercator created the famous and best -known card projection, which is still widespread today despite its enormous distortions.

That is the reason why Greenland looks as big as Africa on Google Maps. There is little distortion near Equato. Distances along the equator are always correct, but nowhere else.

alt = "card projection mercator"> strut: cc 2.0 looking similar? Greenland is as big as Africa

It became the standard card projection for nautical purposes, since it can represent lines with constant true direction-of crucial importance at a time when sailing ships and navigation were only based on the direction!

take a look at thetruesize.com to get an impression of how the Mercator projection (and Google) distort our world view.

alt = "true size of the card website"> thetruesize.com This app shows the true size of countries that are shown incorrectly on Google Maps

galle stereographically: In 1855 the spiritual James Gall presented a map that was supposed to be similar to the Mercator, but with less distortion of the scale and the area near the poles. The cylindrical stereographic projection, based on two standard parallels at 45 ° north and south, was unnoticed when it was announced.

alt = “card projection gall”> strut: CC 2.0 similar to Mercator, but with less distortion near the pole

GALL - PETERS: In 1973, filmmaker Arno Peters presented a cylindrical world map based on the map of James Gall. In contrast to the Mercator projection, Africa is shown in its true size: 14 times larger than Greenland.

It is a further development of Peters' earlier work. Like the map of Gall, the card determines the width 45 ° north and south as the regions on the map that have no distortion.

Alt = “Card projection-Gall-Peters”> Strieb: CC 2.0 Africa is represented in its true size: 14 times larger than Greenland

Lambert Conformal Conic: In 1772 a French-German mathematician and scientist named Johann Heinrich Lambert published seven card projections! His conformal conic card projection, which was considered a revolutionary and still important today, has become a standard for the mapping of large areas on a small scale on medium-sized latitudes such as the USA and Europe

It is not very good for the southern latitudes, which are usually cut somewhere around 30 ° south.

alt = "Map-Projects-Lambert_Conformal_Conic"> Strieb: CC 2.0 Not useful for South Africa, Australia and Argentina

Robinson: Ahhh, my favorite card projection. I like the Robinson because it is more precise and more attractive than the Mercator. The card was developed in the 1960s by Arthur H. Robinson, an American geography professor, because modern card manufacturers were dissatisfied with the distortions of the Mercator projection and wanted a world projection that felt more realistic.

Therefore, the Robinson projection has become more popular than the Mercator projection.

alt = "card projection-robinson"> strut: cc 2.0 my favorite-the Robinson just looks correct

Since it is a pseudocylindrical projection, the standard parallel is located on the equator and still has similar distortion problems to the Mercator projection. However, the area of ​​acceptable distortion is expanded from 15 ° north and south to 45 ° north and south.

There are also fewer distortions in the polar regions. In contrast to the Mercator, the Robinson has the latitudes and length degrees on the map at even intervals.

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Literature recommendations:

Prisoners of geography: Ten cards that explain everything about the world are restricted by geography. Their choices are limited by mountains, rivers, seas and concrete. In order to understand world events, we often concentrate on people, ideas and political movements, but without geography we never have the full picture.

The revenge of geography: What the map about upcoming conflicts and the fight against fate says this provocative, surprising book offers Robert D. Kaplan, the bestselling author of "MONSUN and Balkanister", an insightful new prism through which we can look at global upheavals and upheavals to understand what continents and countries around the world is imminent.

main picture: Javarman/Shutterstock

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