Dependiendo de cuál sea el punto que se considere como centro del mapa, se distingue entre proyecciones polares, cuyo centro es uno de los polos; ecuatoriales, cuyo centro es la intersección entre la línea del Ecuador y un meridiano; y oblicuas o inclinadas, cuyo centro es cualquier otro punto.[28]​.

Se distinguen tres tipos de proyecciones básicas: cilíndricas, cónicas y acimutales.

Cylindrical projection

The Mercator projection, which revolutionized cartography, is cylindrical and conformal. In it, the terrestrial globe is projected onto a cylindrical surface. It is one of the most used, although generally in modified form, due to the great distortions it offers in high latitude areas, which prevents the polar regions from being appreciated in their true proportion. It is used in the creation of some world maps. To correct deformations at high latitudes, pseudocylindrical projections are used, such as Van der Grinten's, which is polyconic, with parallels and circular meridians. It is essentially useful for viewing the entire Earth's surface.[29]​.

conical projection

The conical projection is obtained by projecting the elements of the Earth's spherical surface onto a tangent conical surface "Cone (geometry)"), placing the vertex "Vertex (geometry)") on the axis that joins the two poles.[30]​ Although the shapes presented are of the poles, cartographers use this type of projection to view countries and continents.

There are various types of conical projections:

Azimuthal projection

In the azimuthal or azimuthal projection[31]​ a portion of the Earth is projected onto a plane tangent to the globe at a selected point, obtaining an image similar to the view of the Earth from an interior or exterior point. If the projection is of the first type it is called a gnomonic projection; if it is the second, spelling. These projections offer a greater distortion the greater the distance to the tangential point of the sphere and the plane "Plane (geometry)").[32]​ This type of projection is mainly related to the poles and hemispheres.[33]​

Types of projections:

Modified projections

Currently, most maps are made based on modified projections or a combination of the previous ones, sometimes with several focal points, in order to correct distortions in certain selected areas as much as possible, even when new ones occur in places that are given secondary importance, such as generally large areas of sea. Among the most common are Lambert's polyconic projection, used for educational purposes, and world maps prepared according to the Winkel-Tripel (adopted by the National Geographic Society)[34] and Mollweide projections), which have an ellipse shape and fewer distortions.

Conventional projections were generally created to represent the entire world (world map) and give the idea of ​​maintaining metric properties, seeking a balance between distortions, or simply making the world map "look good".[35]​ Most of these types of projections distort the shapes in the polar regions more than at the equator:.

The mathematics of projection does not allow us to say that any particular cartographic projection can be considered the best of all.[36] Something will always be distorted. Therefore, many projections exist to serve the many uses of maps and their wide range of scales.

Modern national mapping systems typically employ a Transverse Mercator or a close variant for large-scale maps in order to preserve conformity and low scale variation over small areas. For smaller scale maps, such as those covering continents or the entire world, many projections depending on their suitability for the purpose, such as Winkel tripel, Robinson and Mollweide, are in common use.[37] Reference maps of the world usually appear in compromise projections. Due to the distortions inherent in any world map, the choice of projection becomes largely a matter of aesthetics.

Thematic maps typically require an equal area projection so that phenomena per unit area are shown in the correct proportion.[38]​

However, correctly representing area relationships necessarily distorts shapes more than many non-equal area maps.

The Mercator projection, developed for navigation purposes, has often been used on world maps where other projections would have been more appropriate.[39]​[40][41][42]​ This problem has long been recognized even outside professional circles. For example, a New York Times editorial from 1943 states:

A controversy in the 1980s over Peters' map motivated the American Cartographic Association (now the Society for Cartography and Geographic Information) to produce a series of pamphlets (including Which Map Is Best [43]) designed to educate the public about cartographic projections and distortion in maps. In 1989 and 1990, after some internal debate, seven American geographic organizations adopted a resolution recommending against the use of any rectangular projections (including Mercator and Gall-Peters) for reference maps of the world.[44][45]​.

Dependiendo de cuál sea el punto que se considere como centro del mapa, se distingue entre proyecciones polares, cuyo centro es uno de los polos; ecuatoriales, cuyo centro es la intersección entre la línea del Ecuador y un meridiano; y oblicuas o inclinadas, cuyo centro es cualquier otro punto.[28]​.

Se distinguen tres tipos de proyecciones básicas: cilíndricas, cónicas y acimutales.

Cylindrical projection

The Mercator projection, which revolutionized cartography, is cylindrical and conformal. In it, the terrestrial globe is projected onto a cylindrical surface. It is one of the most used, although generally in modified form, due to the great distortions it offers in high latitude areas, which prevents the polar regions from being appreciated in their true proportion. It is used in the creation of some world maps. To correct deformations at high latitudes, pseudocylindrical projections are used, such as Van der Grinten's, which is polyconic, with parallels and circular meridians. It is essentially useful for viewing the entire Earth's surface.[29]​.

conical projection

The conical projection is obtained by projecting the elements of the Earth's spherical surface onto a tangent conical surface "Cone (geometry)"), placing the vertex "Vertex (geometry)") on the axis that joins the two poles.[30]​ Although the shapes presented are of the poles, cartographers use this type of projection to view countries and continents.

There are various types of conical projections:

Azimuthal projection

In the azimuthal or azimuthal projection[31]​ a portion of the Earth is projected onto a plane tangent to the globe at a selected point, obtaining an image similar to the view of the Earth from an interior or exterior point. If the projection is of the first type it is called a gnomonic projection; if it is the second, spelling. These projections offer a greater distortion the greater the distance to the tangential point of the sphere and the plane "Plane (geometry)").[32]​ This type of projection is mainly related to the poles and hemispheres.[33]​

Types of projections:

Modified projections

Currently, most maps are made based on modified projections or a combination of the previous ones, sometimes with several focal points, in order to correct distortions in certain selected areas as much as possible, even when new ones occur in places that are given secondary importance, such as generally large areas of sea. Among the most common are Lambert's polyconic projection, used for educational purposes, and world maps prepared according to the Winkel-Tripel (adopted by the National Geographic Society)[34] and Mollweide projections), which have an ellipse shape and fewer distortions.

Conventional projections were generally created to represent the entire world (world map) and give the idea of ​​maintaining metric properties, seeking a balance between distortions, or simply making the world map "look good".[35]​ Most of these types of projections distort the shapes in the polar regions more than at the equator:.

The mathematics of projection does not allow us to say that any particular cartographic projection can be considered the best of all.[36] Something will always be distorted. Therefore, many projections exist to serve the many uses of maps and their wide range of scales.

Modern national mapping systems typically employ a Transverse Mercator or a close variant for large-scale maps in order to preserve conformity and low scale variation over small areas. For smaller scale maps, such as those covering continents or the entire world, many projections depending on their suitability for the purpose, such as Winkel tripel, Robinson and Mollweide, are in common use.[37] Reference maps of the world usually appear in compromise projections. Due to the distortions inherent in any world map, the choice of projection becomes largely a matter of aesthetics.

Thematic maps typically require an equal area projection so that phenomena per unit area are shown in the correct proportion.[38]​

However, correctly representing area relationships necessarily distorts shapes more than many non-equal area maps.

The Mercator projection, developed for navigation purposes, has often been used on world maps where other projections would have been more appropriate.[39]​[40][41][42]​ This problem has long been recognized even outside professional circles. For example, a New York Times editorial from 1943 states:

A controversy in the 1980s over Peters' map motivated the American Cartographic Association (now the Society for Cartography and Geographic Information) to produce a series of pamphlets (including Which Map Is Best [43]) designed to educate the public about cartographic projections and distortion in maps. In 1989 and 1990, after some internal debate, seven American geographic organizations adopted a resolution recommending against the use of any rectangular projections (including Mercator and Gall-Peters) for reference maps of the world.[44][45]​.