Littrow projection

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Littrow projection of partial hemisphere Littrow projection SW.JPG
Littrow projection of partial hemisphere

The Littrow projection is a map projection developed by Joseph Johann von Littrow in 1833. It is the only conformal, retroazimuthal map projection. As a retroazimuthal projection, the Littrow shows directions, or azimuths, correctly from any point to the center of the map.

Map projection Systematic representation of the surface of a sphere or ellipsoid onto a plane

A map projection is a systematic transformation of the latitudes and longitudes of locations from the surface of a sphere or an ellipsoid into locations on a plane. Maps cannot be created without map projections. All map projections necessarily distort the surface in some fashion. Depending on the purpose of the map, some distortions are acceptable and others are not; therefore, different map projections exist in order to preserve some properties of the sphere-like body at the expense of other properties. There is no limit to the number of possible map projections.

Joseph Johann von Littrow Austrian astronomer

Joseph Johann von Littrow was an Austrian astronomer. In 1837, he was ennobled with the title Joseph Johann Edler von Littrow. He was the father of Karl Ludwig Edler von Littrow and the mentor of the mathematician Nikolai Brashman. His work took him to Russia for a time, which is where his son who succeeded him was born.

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Patrick Weir of the British Merchant Navy independently reinvented the projection in 1890, after which it began to see more frequent use as recognition of its retroazimuthal property spread. Maps based on the Littrow projection are sometimes referred to as Weir Azimuth diagrams. [1]

The projection transforms from latitude φ and longitude λ to map coordinates x and y via the following equations: [2]

where R is the radius of the globe to be projected and λ0 is the longitude desired for the center point.

See also

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References

  1. Snyder, John P. (1993). Flattening the Earth: 2000 Years of Map Projections. Chicago: University of Chicago Press. p. 135.
  2. Snyder, John P.; Voxland, Philip M. (1989). An Album of Map Projections. Professional Paper 1453. Denver: USGS. p. 231. ISBN   978-0160033681 . Retrieved 2014-09-27.