Geocart Projections

What is a projection?

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plate carrée

plane chart

geographic projection

Classifications

Geocart menu class: Cylindric
Cylindric
Equidistant

Graticule

Meridians: Equally spaced straight parallel lines half as long as the Equator.
Parallels: Equally spaced straight parallel lines, perpendicular to and having same spacing as meridians
Poles: Straight lines equal in length to the Equator
Symmetry: About any meridian or the Equator

Scale

True along the Equator and along all meridians
Increases with the distance from the Equator along parallels
Constant along any given parallel; same scale at the parallel of opposite sign

Distortion

Infinitesimally small circles of equal size on the globe (indicatrices) are ellipses except along the Equator, where they remain circles. Areas of the ellipses also vary. Thus, there is distortion of both shape and area.

Other features

Most simply constructed graticule of any projection
Conceptually projected onto a cylinder wrapped around the globe tangent to the Equator
Not perspective

Usage

Many maps during the 15th and 16th centuries
Simple outline maps of regions or of the world or index maps
Used only for the Earth taken as a sphere

Origin

May have been originated by Eratosthenes (275?-195? B.C.) Marinus of Tyre also credited with its invention about A.D. 100

Aspects

Normal is described here.
Transverse aspect is the Cassini projection, which is also applied to the ellipsoid.
Oblique aspect is rarely used.

Other names

Simple Cylindrical
Equidistant Cylindrical (particular form)

Similar projections

If meridians are compressed relative to parallels, the Equirectangular projection results.

Description adapted from J.P. Snyder and P.M. Voxland, An Album of Map Projections, U.S. Geological Survey Professional Paper 1453. United States Government Printing Office: 1989.