Equidistant Conic

A conic projection with equally spaced parallels. Neither conformal nor equal area. Also known as the Simple Conic or Conic projection.

Scale

True along each meridian and along one or two chosen standard parallels, usually but not necessarily on the same side of the Equator. As a rule of thumb, these parallels can be placed at one-sixth and five-sixths of the range of latitudes, but there are more refined means of selection.

Scale is constant along any given parallel.

Distortion

Free of angular and scale distortion only along the one or two standard parallels. Distortion is constant along any given parallel. Compromise in distortion between equal-area and conformal conic projections.

Usage

The most common projection in atlases for small countries. Also used by the Soviet Union for mapping that nation.

Limitations

Use only for a single hemisphere.

Origin

Rudimentary forms developed by Claudius Ptolemy (about A.D. 100). Improvements by Johannes Ryusch in 1508;, Gerardus Mercator in the late 16th century, and Nicholas de l’Isle in 1745.

Limiting Forms

Polar Azimuthal Equidistant projection: if a pole is made the single standard parallel. The cone of projection thereby becomes a plane.

Plate Carree projection: if the Equator is the single standard parallel. The cone of projection thereby becomes a cylinder.

Equirectangular (Cylindrical) projection: if the two standard parallels are symmetrically placed north and south of the Equator.

Options

Specify the first standard parallel and second standard parallel to tailor the projection to the area to be mapped.

Specify the latitude origin and longitude origin to center the map projection to the area to be mapped. Specifying a non-Equatorial origin causes an oblique projection.