AZIMUTHAL PROJECTION: CHARACTERISTICS, TYPES, ADVANTAGES, DISADVANTAGES - GEOGRAPHY - 2025

The azimuthal projection, also called azimuthal and zenithal projection projection is the map projection of the earth on a flat surface. The main intention of this projection is to obtain a view of the globe from the center of it or from outer space.

It is the reflection that is obtained on a tangent plane (for example, a sheet of paper), taking into account the meridians and parallels, which end up transmitting a set of features and characteristics of the sphere to that other element.

Gnomonic azimuthal projection.

In general, the reference points for this projection are usually either pole. However, it can be done from anywhere on Earth. It is important to note that the azimuthal projection refers to the mathematical term "azimuth", which is believed to come from Arabic and refers to distances and trajectories.

Through the azimuthal projection, the closest distances between two points on the planet can be located, taking into account the great circles of the circumference. For this reason, this type of projection is used for great circle navigation, which seeks to follow the path of the great circles to travel the shortest distance between two points.

History

Some scholars claim that the ancient Egyptians were the pioneers in the study of the heavens and the shape of the Earth. Some maps can even be found in sacred books.

However, the first texts related to azimuthal projection appeared in the 11th century. It is from there that the study of geography and maps develops, whose evolution flourished during the Renaissance.

At that time sketches were made on the continents and countries. The first to do so was Gerardo Mercator, who made the famous 156 map. Later, the Frenchman Guillaume Postel would follow, who popularized this projection under the name of "Postel projection", which he used for his 1581 map.

Even today the influence of this projection can be seen in the emblem of the United Nations.

Main features

- The meridians are straight lines.

- The parallels are concentric circles.

- Longitude and latitude lines intersect at 90 ° angles.

- The scale on the elements near the center is real.

- The azimuthal projection generates a circular map.

- In general, the poles are considered as central points for the realization of the projection.

- The resulting maps can preserve values ​​in terms of equidistance, area and shape.

- It is characterized by having radial symmetry.

- The direction is correct as long as it goes from the central point or element to another.

- Generally not used near the equator because there are better projections in this area.

- Presents distortions as it moves away from the center point.

To understand projection of any type, it is important to take into account that it is based on mathematical concepts to obtain the best possible result in terms of the terrestrial image.

For this, the following concepts are considered:

Equidistant projection

It is that projection that preserves distances.

Equivalent projection

It is the projection that preserves the surfaces.

Conformal projection

Preserves the shape or angle relationship between the studied points.

In the end, this indicates that no projection really allows to preserve these three elements since it is mathematically impossible because it takes as reference an element with spherical dimensions.

Main types of azimuthal projection

When there is perspective projection

Stereographic projection

This considers an opposite extreme point on the globe. The most common example is when the poles are used as a reference, although in that case it would be called a polar projection.

It is also characterized by the fact that the parallels become closer as they go towards the center, and each circle is reflected as a semicircle or as a straight line.

Orthographic projection

It is used to have a view of the hemispheres, but from the perspective of outer space. Area and shape are distorted and distances are real, especially those around the equator.

Gnomic projection

In this projection all the points are projected towards a tangent plane, considering the center of the Earth.

It is generally used by navigators and pilots because the circular patterns of the meridians are shown as straight lines, showing shorter routes to follow.

It should be noted that although there are technological advances through which it is easier to find these routes, the use of paper still persists.

When there is no perspective projection

Equidistant azimuthal projection

It is generally used for navigation and travel to the polar areas, which is why air-route distances stand out. The measurements from the center are real.

Lambert azimuthal projection

With this projection it is possible to see the entire Earth but with angular distortions. That is why it is used especially for the construction of atlases, starting from east to west.

Oblique lines allow continents and oceans to be included. Also, among its uses is the mapping of small countries and islands.

Applications

- The azimuthal projection allows orthodromic navigation, which consists of finding the minimum distance from one point to another, from the air or the sea.

- It allows the elaboration of maps for small and compact places, as well as universal atlases.

- Seismologists use gnomic projections to determine seismic waves, since they move in large circles.

- Helps the radio communication system, since operators use azimuthal projection to locate antennas according to the angles established on the maps.

Advantage

- Intercept the Earth according to the different laws on perspectives.

- When the center of the projections is at the poles, the distances are real.

- Provides a great projection of the Arctic and Antarctic maps, as well as the hemispheres.

- The representation of the poles does not show distortion, because it increases at the equator.

Disadvantages

- The distortion will be greater as the distance increases, from a point on the flat surface to the surface of the globe.

- It does not allow to represent the Earth in its entirety, unless it presents distortions.

Articles of interest

Homolographic projection.

Peters projection.

Types of cartographic projections.

Mercator projection.

References

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4. Fundamental of Maping. (2016). In ICSM. Retrieved: February 15, 2018. In ICSM at icsm.gov.au.
5. Azimuthal projection. (2013). In Map Engineering. Retrieved: February 15, 2018. In Engineering Maps of ingenieriademapas.wordpress.com.
6. Azimuthal projection. (sf). On Wikipedia. Retrieved: February 15, 2018. In Wikipedia at es.wikipedia.org.
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