Geocart Projections

What is a projection?

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Hammer retroazimuthal front hemisphere

Parameters: Latitude of origin


Modified azimuthal
Neither conformal nor equal area


Meridians: Central meridian is straight. Other meridians are curved.
Parallels: Curved
Poles: Curved lines
Symmetry: About the central meridian


Extreme distortion of area and shape

Other features

The direction from any point to the center of the map is the angle that a straight line connecting the two points makes with a vertical line. This feature is the basis of the term "retroazimuthal." Scimitar-shaped boundary. Considerable overlapping when the entire sphere is shown.


To determine the direction of a central point from a given location


Presented by H.H. Ernst von Hammer (1858–1925) of Germany in 1910. Independently presented by Edward A. Reeves (1862–1945) and Arthur R. Hinks (1874–1945) of England in 1929.

Similar projections

Craig Retroazimuthal has straight, equally spaced meridians.

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.