Chamberlin trimetric

Parameters: Anchor point 1, Anchor point 2, Anchor point 3

Classifications

Graticule

Meridians: Complex curves.
Parallels: Complex curves.
Poles: Points.
Symmetry: Normally none.

Scale

Approximately correct from three selected widely spaced points on map to any other point on map. Cannot be exactly correct.

Distortion

Low distortion throughout map if three source points are properly placed near map limits.

Usage

Atlas maps of continents by the National Geographic Society and some other atlas publishers.

Similar projections

Azimuthal equidistant projection; true distance and direction from one point.
Two-Point equidistant projection; true distance but not direction from two points.

Origin

Presented by Wellman Chamberlin (1908-76) of the National Geographic Society in 1946.

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.