# Equirectangular

Name | Equirectangular
Alias | Plate Caree
Alias | Equidistant Cylindrical
Alias | Simple Cylindrical
EPSG Code | 9823 (spherical), 9842 (elliptical)
GeoTIFF Code | CT_Equirectangular (17)
OGC WKT Name | Equirectangular
Supported By | GeoTIFF, PROJ.4, OGC WKT

### Projection Parameters

Name | EPSG # | GeoTIFF ID | OGC(OGR) WKT | ESRI PE WKT | PROJ.4 | Units
--- | --- | --- | --- | --- | --- | ---
Latitude of true scale | 3 | ProjStdParallel1 | standard_parallel_1 | Standard_Parallel_1 | +lat_ts | Angular
Latitude of origin | 1 (8801) | ProjCenterLat | latitude_of_origin | (unavailable) | +lat_0 | Angular
Longitude of projection center | 2 (8802/8822) | ProjCenterLong | central_meridian | Central_Meridian | +lon_0 | Angular
False Easting | 6 | FalseEasting | false_easting | False_Easting | +x_0 | Linear
False Northing | 7 | FalseNorthing | false_northing | False_Northing | +y_0 | Linear

### Notes

There are two latitudes that can be important for this projection. The latitude of true scale (lat_ts in PROJ.4, Standard_Parallel_1 in ESRI PE, PSEUDO_STD_PARALLEL_1 in OGR (1.6.0beta), unavailable in EPSG, 6th parm in GCTP) and the latitude of origin (lat_0 in PROJ.4, latitude_of_origin in OGR WKT, unavailable in ESRI PE, unavailable in GCTP). The latitude of origin is just an alternate origin and has no other effect on the equations. Often both are zero.

Generally speaking, if you only have one of these latitudes provided, it is likely the latitude of true scale.

For a period OGR used the name "latitude_of_origin" for the latitude of true scale, in error resulting in much confusion.

Most libraries only implement the spherical version this projection. The rules for deriving a spherical radius from the ellipsoid defined for a coordinate system vary between libraries, causing some confusion and mixed results.

Plate Caree is an alias, but generally implies that the latitude of true scale, and latitude of natural origin are zero. Simple Cylindrical is also an alias with the same assumptions.