The projection of Mercator is a cylindrical cartographic projection that represents the whole terrestrial surface. It was developed by Gerardus Mercator in the sixteenth century, in the year 1569.
This cartographic projection has been heavily criticized for the fact that it distorts forms as it approaches the poles making the land masses look larger than they actually are.
The defenders of Mercator point out that the cartographer did not create this projection with the intention of teaching geography, but of facilitating exploration through navigation.
This aspect differentiates Mercator's projection from previous projections. The maps which had been made so far were descriptive and focused mainly on the representation of relief and watercourses. The Mercator proposal was rather functional.
Today Mercator's projection continues to be one of the most employed. In fact, the global positioning services of Google, Bing, OpenStretMaps and Yahoo rely on this type of cartographic projection.
History
During the sixteenth century information on trade routes and geography was constantly increasing.
For this reason, navigators, explorers and merchants needed more accurate maps. Thus the cartographer and geographer Gerardus Mercator (1512-1594) decided to develop the cylindrical projection that bears his name.
How does Gerardus Mercator's projection work?
To get an idea of how Mercator's projection works, we just have to imagine that we have a translucent earth globe.
This globe will be wrapped in a paper cylinder, so that the line of the Ecuador is the only point of contact between the globe and the cylinder.
As it is a projection is necessary the intervention of light. To realize Mercator projection the light source must be located in Ecuador, on the side opposite the point of contact between the globe and the paper.
In this way, the light will project the figure of the earth masses on the paper cylinder. The forms closest to Ecuador will be almost perfectly projected.
However, as they move away from the parallel, the forms become distorted and enlarged. For this reason, it is observed that Greenland is the size of Africa when in fact it is the size of Mexico.
Advantages of Mercator projection
1- Explore the world
Before Mercator's projection, there were already maps showing the full extent of planet Earth.
However, this was the first that provided people with the means to explore and navigate across the seas. Mainly, this projection is useful for tracing routes with a steady course in a straight line.
In addition to creating a projection, Mercator published a geometric formula that corrected the distortion presented on its map. These calculations enabled seafarers to transform projection measurements into degrees of latitude by facilitating navigation.
Like any flat rendering of the Earth, Mercator's projection presents distortion. The globe is the only true representation of the earth's surface.
In spite of this, the fact that these are so small makes them impractical for navigation. For this reason, the projection of Mercator is still preferred.
2- Calculations of this projection are simpler than those of other projections
The mathematics behind the Mercator projection are much simpler than other projections today. For this reason, online mapping services prefer its use.
The applications of Google Maps, Bing Maps and OpenStreetMaps are based on Mercator projection.
3- Keep the scales
The projection of Mercator is proportional. This means that to compensate for the north-south distortion (from pole to pole), an east-west distortion is also introduced.
Other projections can make a square building look rectangular, because the distortion exists in only one direction.
On the other hand, because it is proportional, the distortion generated by Mercator does not make the objects appear more elongated or flattened, but simply larger.
This is another reason why the cartography web services use this type of projection and not others.
4- Angles are represented correctly
The projection of Mercator has the property of representing the angles as they are. If in the real plane there is an angle of 90 ° the projection will show an angle of the same amplitude.
This is another reason why Google Maps and other similar applications prefer Mercator before other projections.
Disadvantages
1- Distortion of the Earth's surface
As Mercator's projection moves away from the equator, the representation of the Earth's surface is distorted. This distortion makes the shapes found at the poles look bigger than they really are.
Mercator's projection shows that Greenland is the size of Africa, that Alaska is larger than Brazil and that Antarctica is an infinite expanse of ice.
In fact, Greenland is the size of Mexico, the territory of Alaska is 1/5 that of Brazil and Antarctica is a little larger than Canada.
As a result, business charts for educational purposes often do not employ Mercator projection, so as not to create problems in the student learning process. However, they are still used in the representation of areas near Ecuador.
2- Polar zones are not represented
Because the projection of Mercator is based on a cylinder, it is difficult to represent the polar zones of the planet Earth. For this reason, the poles are not included in this type of cartographic projection.
Examples of Mercator projection
One of the best examples of Mercator projection is Google Maps. This is a global positioning software developed in 2005.
Bing Maps and OpenStreetMaps are other of the cartography web services that use the projection of Mercator.
References
- Cylindrical Projection: Mercator. Retrieved on October 13, 2017, from gisgeography.com
- Mercator projection. Retrieved on October 13, 2017, from wikipedia.org
- Mercator projection (cartography). Retrieved on October 13, 2017, from britannica.org
- Mercator projection. Retrieved on October 13, 2017, from geography.hunter.cuny.edu
- Mercator projection. Retrieved on October 13, 2017, from dictionary.com
- Mercator projection. Retrieved on October 13, 2017, from merriam-webster.com
- Mercator Projection v. Gall-Peters Projection. Retrieved on October 13, 2017, from businessinsider.com
- Mercator's Projection. Retrieved on October 13, 2017, from math.ubc.ca