Geocart Projections

What is a projection?

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Geocart menu class: Lenticular
Modified azimuthal
Neither conformal nor equal area


Meridians: Central meridian is a straight line half the length of the Equator. Other meridians are complex curves, equally spaced along the Equator and concave toward the central meridian
Parallels: Equator is straight. Other parallels are complex curves, equally spaced along the central meridian and concave toward the nearest pole.
Poles: Points
Symmetry: About the Equator and the central meridian


True along the Equator and the central meridian


Moderate shape and area distortion

Other features

Elliptical border. An equatorial aspect of one hemisphere of the Azimuthal Equidistant projection, on which horizontal coordinates have been doubled and meridians have been given twice their original longitudes.


Design inspired H.H. Ernst von Hammer to develop his elliptical projection


David Aitoff (or Aitow) (1854–1933) in 1889

Similar projections

Hammer (Elliptical), equal area and mistakenly called Aitoff in the early 20th century
Briesemeister, an oblique modification of the Hammer
Eckert-Greifendorff, a modification of the Lambert Azimuthal Equal-Area projection inspired by the Hammer
Winkel Tripel is a combination of the Aitoff and Equidistant Cylindrical projections.

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.