The Quartic Authalic projection is a pseudocylindrical, equal area projection that is used primarily for world maps. It was first presented by Karl Siemon in 1937, and then later presented independently by Oscar Sherman Adams in 1945. This projection serves as a basis for the McBryde-Thomas Flat Polar Quartic projection.
The central meridian is depicted as a straight line 0.45 as long as the Equator. Other meridians are equally spaced curves, concave toward the central meridian. The parallels are straight parallel lines perpendicular to the central meridian. These are spaced farthest apart near the Equator, but gradually grow closer spaced when moving toward the poles. The poles are represented by points.
Distortion is significant near the outer meridians, at high latitudes, but is less than in the Sinusoidal projection. There is no distortion and scale is true along the Equator. Scale is constant along any given latitude.
The "QuarticAuthalic" Projection has the following Parameters:
|
Parameter Name |
Parameter String |
Units |
|
Longitude of the Center of the Projection |
central_meridian |
|
|
False Easting |
false_easting |
|
|
False Northing |
false_northing |
NOTE: Only a spherical form of this projection is used. The semi-major axis of the ellipsoid (sphere) is used for forward and inverse projection from grid to geodetic coordinates within the system wherein this projection is incorporated.