Découvrez les différentes projections en cartographie : exploration des perspectives géographiques

Discover the different projections in cartography: exploring geographical perspectives

Cartography is a fascinating discipline that allows us to represent our world in a visual and understandable way. However, it is important to understand that the Earth is a three-dimensional sphere, while maps are two-dimensional planar representations. To achieve this conversion, cartographers use map projections, which are mathematical methods for projecting the Earth's surface onto a plane. There are many ways to achieve this projection, each having its advantages and disadvantages. These projections can be classified into three main categories: cylindrical projections, conical projections and azimuthal projections. In this article, we will explore the different projections in mapping and understand how they influence the way we perceive our planet.

Cylindrical projections

Cylindrical projections are based on the idea of ​​projecting the earth's surface onto a cylinder tangent to the equator or another parallel. One of the most commonly used cylindrical projections is the Mercator projection. It is appreciated for its simplicity and its ability to represent directions precisely. However, the Mercator projection distorts the sizes and distances of the polar regions, causing the dimensions of land away from the equator to be exaggerated.
Mercator projection
Mercator projection (source: Geo Projections)

Conical projections

Conic projections are based on the idea of ​​projecting the earth's surface onto a cone tangent to a parallel or intersecting two parallels. The equidistant conic projection is a popular projection that preserves distances and scales along selected parallels, but results in larger distortions the further away from the reference parallels. One of the oldest and most famous conic projection maps is none other than Ptolemy's map.

Equidistant conical projection

Equidistant conic projection (source: Geo Projections)

Azimuthal projections

Azimuthal projections are based on the idea of ​​projecting the Earth's surface onto a plane tangent to a central point on the Earth. One of the most well-known azimuthal projections is the orthographic projection, which presents a perspective view from a point at infinity. This projection is often used to represent the poles, but it significantly distorts regions far from the point of tangency.

Equidistant azimuthal projection

Equidistant azimuthal projection (source: Geo Projections)

Special screenings

Besides cylindrical, conical and azimuthal projections, there are many other special projections used to meet specific needs. For example, the Robinson projection is an attempt to balance the size and shape of regions. The Mollweide projection, for its part, is an equivalent projection which preserves the areas of the regions.
Mollweide screening
Mollweide projection (source: Geo Projections)


Each projection has its advantages and disadvantages, and no single projection can accurately represent the curved surface of the Earth. Cartographers must consider many factors, such as the study area, the type of data being mapped, and the purpose of the map, to select the most suitable projection.
By understanding the different projections in mapping, we are better equipped to interpret maps and recognize the distortions inherent in each projection.
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