Geocart Projections

What is a projection?

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Parameters: Parallel curvature 0 << W ≤ 1.0


Modified azimuthal
Equal area


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


Decreases along the central meridian and the Equator with distance from the center


Moderate. Less shearing action on the outer meridians near the poles than there is on pseudocylindrical projections.

Other features

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


Whole-world maps, also in interrupted and condensed forms


Presented by H.H. Ernst von Hammer (1858–1925) of Germany in 1892


Normal and oblique are both in use.

Other names

Mistakenly called Aitoff projection in the early 20th century.

Similar projections

Briesemeister, a modified oblique Hammer
Eckert-Greifendorff, a further modification of the Lambert Azimuthal Equal-Area projection

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.