Eckert IV – Global Mapper

The Eckert IV and Eckert VI were created by Max Eckert in 1906, and are used for world maps. Both are Pseudocylindrical projections whose central meridian is a straight line. 180th meridians of the Eckert IV projection are cemicircle, and all other meridians are equally spaced elliptical Arcs. Meridians on the Eckert VI projection are equally spaced sinusoidal curves. In both projections, the parallels are unequally spaced straight lines parallel to one another, and the Poles are straight lines half as long as the equator. Scale is true along latitudes 40º30' for the Eckert IV projection, and 49º16' for Eckert VI.

The "EckertIV" Projection has the following Parameters:

Parameter Name	Parameter String	Units
Longitude of the Center of the Projection	central_meridian	AngularValue
Radius of the Sphere	spherical_radius	LinearValue
False Easting	false_easting	LinearValue
False Northing	false_northing	LinearValue

Note: If the spherical_radius parameter is set to a value greater than zero, then it will be used as the radius of the sphere. If this parameter is set to a value less than or equal to zero, then the SemiMajor radius of the Ellipsoid will be used as the radius of the sphere.