Map Projection
Definition
A map projection is a systematic transformation of the latitudes and longitudes of locations on the surface of a sphere or an ellipsoid into locations on a plane. Map projections are needed for creating maps, all map projections distort the surface in some fashion. Depending on the purpose of the map, some distortions are acceptable and others are not; therefore, different map projections exist in order to preserve some properties of the sphere-like body at the expense of other properties.
What is Map Projection?
Map Projection is a critical aspect of the Geographic Information System (GIS) and Cartography. Put simply, map projections aim to turn the 3-dimensional globe, i.e., the Earth, into a 2-dimensional plane, i.e., a map. Each and every map we use, from Google Maps to in-car GPS, uses some form of a projection to represent the Earth's surface.
Due to the mathematical impossibility of faithfully depicting 3D space on a 2D surface without distortion, all map projections introduce some level of distortion, either in shape, area, distance, or direction. Some projections aim to reduce distortion in one or two of these properties at the expense of drastically increasing it in the others, while others aim to strike a balance and minimize distortion in all properties, thereby not perfectly preserving any.
Selecting the right map projection depends on the requirements of the map's intended use. For instance, for navigation, the Mercator projection is often used as it preserves angles and shapes around small areas, particularly beneficial for sea and air navigation.
FAQs
What are the three types of projections?
There are three basic types of map projections: cylindrical, conic, and azimuthal. In the cylindrical projection, a cylinder surrounds the globe and the geographical details are projected onto the cylindrical surface, which can then be unrolled into a flat surface. In the conic projection, a cone is placed over the Earth's sphere and the details are projected onto the cone, which can then be flattened into a plane. Azimuthal projections involve projecting points from the globe onto a plane.
Why are map projections necessary?
Map projections are necessary to convert the three-dimensional Earth into a two-dimensional map while preserving as much important information as possible. Since it's impossible to depict a spherical shape on a flat surface without causing some distortion, map projections help reduce these distortions in area, distance, shape, or direction.
What is distortion in map projections?
Distortion in map projections refers to the changes that occur while transforming Earth's 3D surface to a 2D map. These changes may affect the accuracy of areas, shapes, distances, or directions. All map projections will have some degree of distortion as it is mathematically impossible to project a 3D surface onto a 2D surface without causing changes.
Which map projection is the most accurate?
There is no 'most accurate' map projection as the accuracy depends on the intended use of the map. Different projections are better suited for different tasks. However, the WGS84 model, used by the Global Positioning System, is often considered highly accurate as it minimizes distortions in certain areas on Earth.
