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What Is a Map Projection?

Humans have known that the shape of the Earth resembles a sphere and not a flat surface since classical times, and possibly much earlier than that. If the world were indeed flat, cartography would be much simpler because map projections would be unnecessary.

A map projection is a procedure that flattens a curved surface such as the Earth onto a plane. Usually this is done through an intermediate surface such as a cylinder or a cone, which is then unwrapped to lie flat. Consequently, map projections are classified as cylindrical, conical, and azimuthal (a direct transformation of the surface of part of a spheroid to a circle). See The Three Main Families of Map Projections for discussions and illustrations of how these transformations work. The toolbox can project both vector data and raster data.

Mapping Toolbox™ map projection libraries feature dozens of map projections, which you principally control with axesm. Some are ancient and well-known (such as Mercator), others are ancient and obscure (such as Bonne), while some are modern inventions (such as Robinson). Some are suitable for showing the entire world, others for half of it, and some are only useful over small areas. When geospatial data has geographic coordinates, any projection can be applied, although some are not good choices. For more information, see Projection Distortions.

To view a list of supported projections, see Summary and Guide to Projections. For further reading, Bibliography provides references to books and papers on map projection.

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