Equirectangular projection

An equirectangular projection of the Earth; the standard parallel is the equator.

The equirectangular projection with Tissot's Indicatrix of deformation

Template:Portalpar The equirectangular projection (also called the equidistant cylindrical projection or geographic projection is a very simple map display invented about 100 AD. The projection maps Longitude and Latitude (vertical and horizontal map lines) to evenly spaced straight lines. Because of the distortions introduced by this display, it has little use in navigation and finds its main use in the theme of an area.

Definition

$x=\lambda \cos(\phi _{1})\,$

$y=\phi \,$

where

$\lambda \,$ is the longitude from the central meridian of the projection,

$\phi \,$ is the latitude

$\phi _{1}\,$ are the standard parallels (north and south of the equator) where the scale of the projection is true.

Note that on the right side of the equation, the coordinates $\lambda \,$ and $\phi \,$ are linear, not angular, measurements. The point $(0,0)$ is at the center of the resulting projection (in particular, this requires the input range to be $[-\pi ,\pi ]$ rather than $[0,2\pi ]$). This projection maps longitude and latitude directly into x and y, hence is sometimes called the longitude-latitude projection.

The plate carrée (French, for "flat square"), is the special case where $\phi _{1}\,$ is zero.

See also

• Cartography
• Cassini projection
• Gall-Peters projection with resolution regarding the use of rectangular world maps
• Panorama

External links

• Global MODIS based satellite map The blue marble: land surface, ocean color and sea ice.
• Table of examples and properties of all common projections, from radicalcartography.net.
• Panoramic Equirectangular Projection, PanoTools wiki.