Bonne projection

A Bonne projection is a pseudoconical equal-area map projection, sometimes called a dépôt de la guerre or a Sylvanus projection. Although named after Rigobert Bonne (1727-1795), the projection was in use prior to his birth, in 1511 by Sylvano, Honter in 1561, De l'Isle before 1700 and Coronelli in 1696 ["Flattening the Earth: Two Thousand Years of Map Projections", John P. Snyder, 1993, pp.60-62, ISBN 0-226-76747-7] .

The projection is:

:$x\; =\; ho\; sin\; E,$:$y\; =\; cot\; phi\_1\; -\; ho\; cos\; E,$

where

:$ho\; =\; cot\; phi\_1\; +\; phi\_1\; -\; phi,$:$E\; =\; frac\; \{lambda\; cos\; phi\}\; \{\; ho\}$

and $phi,$ is the latitude, $lambda,$ is the longitude from the central meridian, and $phi\_1,$ is the standard parallel of the projection [ [http://pubs.er.usgs.gov/usgspubs/pp/pp1395 "Map Projections - A Working Manual"] , USGS Professional Paper 1395, John P. Snyder, 1987, pp.138-140] .

Special cases of the Bonne projection include the sinusoidal projection, when $phi\_1,$ is zero, and the Werner projection, when $phi\_1,$ is $pi\; /\; 2,$.

Parallels of latitude are concentric circular arcs, and the scale is true along these arcs. On the central meridian and the standard latitude shapes are not distorted.

References

External links

* [http://www.cybergeo.eu/index3977.html Cybergeo article]
* [http://exchange.manifold.net/manifold/manuals/5_userman/mfd50Bonne.htm Bonne Map Projection (manifold.net)]
* [http://www.radicalcartography.net/?projectionref Table of examples and properties of all common projections] , from radicalcartography.net
* [http://www.uff.br/mapprojections/Bonne_en.html An interactive Java Applet to study the metric deformations of the Bonne Projection]
* [http://mathworld.wolfram.com/BonneProjection.html Bonne Projection (wolfram.com)]