Parameters: Latitude of origin
Geocart menu class: Azimuthal
Geocart family: Retroazimuthal
Neither conformal nor equal area
Meridians: Equally spaced straight parallel lines
Poles: Curved lines
Symmetry: About the central meridian
Extreme distortion of shape and area
The direction is correct from any location on the map to a central point.
Considerable overlapping when entire sphere is shown
To show, for example, the correct direction toward Mecca, from any point on the map, by measuring the angle from North. Because the meridians are straight parallel lines, this angle can be readily measured.
Presented by James Ireland Craig (1868-1952) of the Survey of Egypt in 1909
Hammer Retroazimuthal has curved, unequally spaced meridians.
Hans Maurer of Germany in 1919 and J.E. Jackson of England in 1968 devised retroazimuthal projections characterized by straight, parallel, unequally spaced meridians.
Carl Schoy presented a projection in 1913 having meridians that are straight, equidistant, and parallel but parallels that are curved, so that all great circles passing through the central point are straight lines at their true azimuths from center. It is not retroazimuthal, nor is its distortion only a function of distance from the center, as it is on most azimuthal 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.