Map Projections

Have you ever looked at a classic world map and thought, 'this doesn't look quite right'? Well, you'd be completely correct. World maps are just projections; they're not actually that accurate. In fact, our most commonly known map, or at least the most recognisable one, is completely wrong in reference to scale. But why are world map projections so wrong? Is there more than one type of map projection? What are the problems with map projections? Let's find out.

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Table of contents

    World Map Projections

    Maps have been a vital way of displaying information about our world for hundreds of years. They are not only important to geographers, but throughout history, maps have been used to display anything from trade routes to hunting locations. Maps are projections of our earth.

    A map projection is a method of showing our earth (or smaller sections of it) on a flat surface. It involves transferring latitudes and longitudes of our spherical earth, which is 3D, onto a flat and 2D surface. Our world isn't flat, but when we look at maps, it's been manipulated in a way that we can view it from a flattened perspective.

    Map Projections Earth with black background StudySmarterFig. 1 - how would you project our spherical earth onto something flat?

    Why are map projections important?

    If it were easy to do so, the world could be represented in its natural form; a sphere. This means we'd carry our own globes wherever we went. This would be relatively impractical, however. Globes are also useless at showing detailed information; imagine trying to find the directions to the local bakery using your pocket globe!

    How does this projection work?

    On a globe, there are lines of latitude and longitude. A latitude line is horizontal, showing the distance from the equator (north or south). Longitude lines are vertical, measuring east and west of the Meridian line, which runs through Greenwich in England.

    Map Projections Latitude and Longitude of the Earth diagram StudySmarterFig. 2 - Latitude and Longitude lines of the Earth.

    Upon projection, these latitude and longitude lines are switched to the Cartesian Coordinate System. This is just the X and Y axis most familiar in mathematic studies. To visualise this projection, think about placing a piece of paper over a globe; this is how a map can be constructed. If this paper is placed over a globe, it won't fit properly, as they are both different shapes. This means either the paper or the globe somehow needs to change to accommodate each other (in this case, the paper). This is known as distortion. When the paper touches the globe, there will be an accurate projection. When the paper is further away from the globe, this distortion will occur.

    Types of Map Projections

    There are 3 different types of map projections. They all project the world in slightly different ways, providing different levels of distortion.

    Azimuthal

    This map projection is flat-based, also named a plane projection. From the viewpoint of the top or bottom of the globe, the projection can display one/part of the hemispheres. It produces a circular map. This isn't the most common of map projections.

    Map Projections Azimuthal Projection diagram StudySmarterFig. 3 - A flat/plane-based projection, producing a circular map.

    Conical

    For these projections, paper can be wrapped around a part of the globe in a cone shape. These kinds of maps won't show the entire globe because the distortion would be too large, but rather sections or hemispheres of the globe. These produce a half-moon-shaped map when the cone shape is spread out.

    Map Projections Conical Projection diagram StudySmarterFig. 4 - A cone shape projection, producing a half-mood-shaped map.

    Cylindrical

    This projection uses a rectangle map with straight coordinate lines (both vertical and horizontal), and when you wrap it around a globe, it produces a cylinder or tube shape when the edges of the paper touch each other. These maps are accurate at the equator; however, the north and south poles become very distorted, where the earth starts to curve. With these kinds of projections, it becomes easy to visualise the whole world, even if the accuracy is not so high.

    Map Projections Cylindrical Projection diagram StudySmarterFig. 5 - a cylinder/tube-shaped projection, producing a rectangle map.

    Mercator Projection

    As geographers, this term will be familiar. This is the world's most well-known and most recognised map projection. The Mercator projection is a cylindrical map created in 1569 but Gerardus Mercator. This projection was widely used in schools, and even Google used it until 2018. Although the Mercator projection has problems, it is still one of the most widely used map projections. On this projection, the most accurate projection is closest to the equator, but as you move away from the equator, more distortion occurs. As you can see on the image below, countries further from the equator are not accurate sizes and appear stretched. Greenland and Africa look to be the same size, but really, Africa is actually 14 times larger than Greenland.1 On Mercator's map, Antarctica is bigger than all the continents, but in reality, Antarctica is about the same size as the US and Mexico put together.

    Map Projections Mercator Projection map StudySmarterFig. 6 - The Mercator Projection

    The Mercator projection was primarily used for nautical and marine activities; this projection displays the constant true direction. This means that the straight lines on the map are equal to the compass direction, allowing sailors to plot their routes and make their way around the world.

    Did you know that Gerardus Mercator also coined the famous cartography term, the atlas?

    Different Map Projections

    Alongside the most famous Mercator projection, many other map projections exist. There are hundreds of different map projections, all displaying our world in different ways. Each map has its own level of distortion. There are many different types of map projections for several reasons:

    • Maps are used for different activities - some are used for navigational purposes, whilst others are needed to look more directly at countries and continents.
    • Each projection distorts differently, keeping some areas accurate whilst others highly distorted.
    • One projection isn't enough; it's almost impossible to accurately project the whole world on one map.

    Let's explore some of the other map projections that are commonly seen today.

    The Robinson Projection

    Created in 1961 by Arthur Robinson, the Robinson projection is known as a pseudo-cylindrical projection. On this map, latitude lines are straight, just like on the Mercator projection. However, the longitudinal lines are curved and become increasingly more curved further from the Meridian. Although there is distortion across the map, especially near the poles, it is relatively low level. This map was designed more artistically to make it look more like an accurate representation of the world.

    Map Projections Robinson Projection map StudySmarterFig. 7 - The Robinson Projection

    The Gall-Peters Projection

    This map, created by James Gall and Arno Peters, represents countries more proportionally and accurately. Just like the Mercator projection, it is a cylindrical projection with a similar distortion (more accurate at the equator, less towards the poles). However, the countries are all the correct sizes. This particular map is now used globally, even by the United Nations. Some people criticise this projection, as although the countries are the right size, they are still distorted (through stretching), making the countries have incorrect angles and shapes.

    Map Projections Gall Peters Projection map StudySmarterFig. 8 - The Gall-Peters Projection

    The Winkel Tripel Projection

    This azimuthal projection was created by Oswald Winkel in 1921. The word Tripel comes from the German term for merging three things together. For this map, Winkel tried to reduce the distortion of three elements; area, distance, and direction. However, distortion still exists. Parallel lines have some curvature, and longitude lines curve further as they move away from the meridian. In 1998, the National Geographic Society began using this map as the dominant world map.2

    Map Projections Winkel-Tripel Projection map StudySmarterFig. 9 - The Winkel Tripel Projection

    In this map, the orange dots represent the Tissot Indicatrix. This is a method of showing the level of distortion on a projected map. Each dot shows the level of distortion at that particular point; they are more commonly found when longitude and latitude lines meet. Tissot Indicatrix can actually be visualised in the same way as map projections; if equal-sized dots are drawn at regular points across a globe, and then the globe is projected onto a flat surface, those dots become distorted. The dots may change in shape or size depending on the type of distortion.

    AuthaGraph

    The AuthaGraph was created in 1999 by Hajime Narukawa, and is useful for reducing distortions while still producing a rectangular map. This design, once folded, can produce a globe. Naruwaka split the globe up into 96 triangles, projecting these triangles onto a tetrahedron (pyramid with a triangle base). Once unfolded, the tetrahedron becomes a rectangle, displaying the projected world. In this map, countries are proportionate; however, shapes are slightly distorted, some countries are in different locations compared to other maps, and longitude and latitude lines are more sporadically laid out.

    Map Projections AuthaGraph map StudySmarterFig. 10 - AuthaGraph Projection

    Other well-known examples of map projections include:

    • Dymaxion map
    • Sinu-Mollweide
    • Good's Homolosine
    • Cylindrical Equal Area
    • Peirce Quincuncial
    • Stereographic
    • Lambert Conformal Conic

    Problems with Map Projections

    One of the main problems with map projections is the lack of accuracy. Our world is spherical, and trying to project this onto a flat surface will never produce entirely accurate results. In one way or another, whichever projection you use, the information will be distorted, which means that any map projection is going to have some inaccuracy at some level. Even the super-accurate AuthaGraph distorts the Arctic in a small way, and the orientation of countries is incorrect.

    Some critics say that projections can also be biased. Particularly the Mercator projection, which is argued to be a Eurocentric map. On this map, the so-called Global North of the world is larger than the respective Global South. Europe is also directly centred in the middle of the map, drawing our attention to this area rather than the rest of the world. During colonial times, having European powers at the forefront of world maps fitted perfectly, being advantageous to European colonial countries.

    Projecting a spherical shape onto a flat plane will never be without problems and inaccuracies. Which map do you think projects the world in the best way?

    Map Projections - Key takeaways

    • Map projections are a way of representing our spherical world on a flat surface by transferring longitude and latitude lines to X and Y coordinates.
    • There are 3 main types of map projection; azimuthal, conical, and cylindrical.
    • One of the most well-known map projections is the Mercator Projection.
    • Other famous map projections include the Robinson projection, Gall-Peters projection, Winkel-Tripel projection, and the AuthaGraph, but there are many more.
    • Projecting maps is difficult. Therefore there are many problems associated with the process.

    References

    1. Bec Crew, This animated map shows the true size of each country, nature index, 2019.
    2. esri, Winkel Tripel, ArcGIS Pro.
    3. Fig. 6: mercator projection, (https://commons.wikimedia.org/wiki/File:Mercator_projection_Square.JPG), by Daniel R. Strebe (https://commons.wikimedia.org/wiki/User:Strebe), Licensed by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/).
    4. Fig. 7: robinson projection, (https://commons.wikimedia.org/wiki/File:Robinson_projection_SW.jpg), by Daniel R. Strebe (https://commons.wikimedia.org/wiki/User:Strebe), Licensed by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/).
    5. Fig. 8: gall peters projection, (https://commons.wikimedia.org/wiki/File:Gall%E2%80%93Peters_projection_SW.jpg), by Daniel R. Strebe (https://commons.wikimedia.org/wiki/User:Strebe), Licensed by CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/).
    6. Fig. 10: authagraph projection, (https://commons.wikimedia.org/wiki/File:Projection_AuthaGraph.png), by Felagoth, Licensed by CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/).
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    Frequently Asked Questions about Map Projections

    What are map projections?

    Map projections are a way of showing the spherical earth on a flat surface.

    Why are map projections needed?

    Map projections are needed for practicality. Globes are difficult to carry or use, and are not useful for showing detailed information.

    Why are map projections distorted?

    Map projections end up with distortion, as our world is spherical. Projecting a sphere onto a flat map will always produce some form of distortion.

    What are the most common map projections?

    The most common map projection is the Mercator projection. Other well-known map projections include the Robinson projection, the Gall-Peters projection, the Winkel Tripel projection, and the AuthaGraph, although there are many others.

    What is the main difference between types of map projections?

    The main difference between the types of map projections is the level or type of distortion.

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