Equal Area Cylindrical

The Equal Area Cylindrical projection, or Lambert Cylindrical projection, or Lambert cylindrical equal-area projection, is a map projection based on a cylinder that is most suitable for world maps where area distortion must be kept to a minimum.

Devised by Johann Heinrich Lambert in 1772, it is the fourth of seven projections invented by him. A series of modifications were proposed by Gall in 1855, Behrmann in 1910 and others. Very similar projections were offered by Trystan Edwards of England in 1953, and a re-named copy of the Gall presented by Arno Peters of Germany in 1967. They were presented as revolutionary and original concepts rather than as modifications or copies of the prior projections.

Despite the shape distortion in some portions of a world map, this projection is well suited for equal-area mapping of regions which are predominantly north-south in extent, which have an oblique central line, or which lie near the Equator.

Modifications of Equal Area Cylindrical projections
Even with its various proposed modifications (such as the Gall projection), distortions are so great that there has been little use of any of the forms for world maps by professional cartographers, many of whom have strongly criticized the intensive promotion in the non-cartographic community which has accompanied the political promotion of the re-named Gall modification (the infamous Peters projection).

Peters projection
In 1967, Dr. Arno Peters devised a map based on Gall's orthographic projection and presented it in 1973 as a "new invention." He promoted it as a superior alternative to the Mercator projection, which was suited to navigation but also used commonly in world maps. The Mercator projection increasingly inflates the sizes of regions according to their distance from the equator. This inflation results, for example, in a representation of Greenland that is larger than Africa, whereas in reality Africa is 14 times as large. Since much of the technologically underdeveloped world lies near the equator, these countries appear smaller on a Mercator, and therefore, according to Peters, seem less significant. On Peters's projection, by contrast, areas of equal size on the globe are also equally sized on the map. By using his "new" projection, poorer, less powerful nations could be restored to their rightful proportions. This reasoning has been picked up by many educational and religious bodies, leading to adoption of the Gall–Peters projection among some socially concerned groups.

Peters's original description of the projection for his map contained a geometric error that, taken literally, imply standard parallels of 46°02' N/S. However the text accompanying the description made it clear that he had intended the standard parallels to be 45° N/S, making his projection identical to Gall's orthographic.

Dr. Peters received his doctorate at the University of Berlin in 1942, writing his dissertation on political propaganda, and many cartographers questioned not only the validity of his claim of creating a new projection (one that was identical to Gall's) but also if there were political motivations behind his promotion of the projection.

More Information

 * Cylindrical Projections, Carlos A. Furuti website, www.progonos.com.
 * Peters projection, Carlos A. Furuti website, www.progonos.com.
 * The Nomenclature and Classification of Map Projections Empire Survey Review No. 51, Vol VII January 1944 Pages 190-200 ; L.P. Lee, Lands Survey Department, Wellington, N.Z.
 * Matching the Map Projection to the Need
 * List of ESRI-supported map projections
 * Weisstein, Eric W. Map Projections. From MathWorld--A Wolfram Web Resource.
 * Map Projections''. Atlas of Canada.
 * Cartographical Map Projections'', Carlos A. Furuti website, www.progonos.com.
 * Elements of Map Projection. (26 MB download) U.S. Coast and Geodetic Survey, Special Publication 68 (1938).
 * Map Projections. USGS Publications. December 2000.
 * What are map projections? ArcGIS 10 Online Help
 * University of Colorado at Boulder - Map Projection Overview with Illustrations
 * Data Projections. GeoCommunity Web site.
 * Wiki.GIS.com - Types of Projections