Gall Stereographic projection

In the Gall Stereographic projection, developed by James Gall in 1885, is a cylindrical, world map projection in which it is assumed that a cylinder cuts the globe at the 45 degrees N and 45 degrees S parallels. The meridians are straight vertical lines spaced correctly on the two 45 degree parallels. The parallels are horizontal and their distance is determined by projecting each meridian from its antipodal point on the equator upon the secant cylinder. Only the 45 degree parallels are true to scale; in the equatorial regions the map is reduced in scale; toward the poles the scale is exaggerated increasingly, but not so much as in the Mercator projection.

The central cylindrical projection is formed by projecting the surface of the globe from its center upon a cylinder tangent to the equator. The cylinder is then cut open along one of the meridians and laid out flat. This projection exaggerates high latitudes even more than Mercator’s, and it used only for astronomical purposes. The cylindrical equal-area projection is developed by projecting the surface of the globe, with horizontal rays from its axis, upon a cylinder tangent to the equator. Because of its extreme distortion at higher latitudes, this too is rarely used.

More Information

 * Cylindrical Projections Carlos A. Furuti website
 * 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