Directory of Map Projections

What is a projection?

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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.

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 cylindric projections.


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

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.