Eckert II Projection
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The Eckert II projection is an equal-area
pseudocylindrical In cartography, map projection is the term used to describe a broad set of Transformation (function) , transformations employed to represent the two-dimensional curved Surface (mathematics), surface of a globe on a Plane (mathematics), plane. In ...
map projection In cartography, map projection is the term used to describe a broad set of transformations employed to represent the two-dimensional curved surface of a globe on a plane. In a map projection, coordinates, often expressed as latitude and longitud ...
. In the equatorial aspect (where the equator is shown as the horizontal axis) the network of longitude and latitude lines consists solely of straight lines, and the outer boundary has the distinctive shape of an elongated
hexagon In geometry, a hexagon (from Ancient Greek, Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple polygon, simple (non-self-intersecting) hexagon is 720°. Regular hexa ...
. It was first described by Max Eckert in 1906 as one of a series of three pairs of pseudocylindrical projections. Within each pair, the meridians have the same shape, and the odd-numbered projection has equally spaced parallels, whereas the even-numbered projection has parallels spaced to preserve area. The pair to Eckert II is the
Eckert I projection Eckert may refer to: People * Allan W. Eckert (1931–2011), American historical novelist * Andrea Eckert (born 1958), Austrian actress * Charles R. Eckert (1868–1959), U.S. congressman from Pennsylvania * Ernst R. G. Eckert (1904–2004), Germa ...
.


Description

The projection is symmetrical about the straight
equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
and straight central meridian. Parallels vary in spacing in order to preserve areas. As a pseudocylindric projection, spacing of meridians along any given parallel is constant. The poles are represented as lines, each half as long as the equator. The projection has correct scale only on the central meridian at latitudes 55°10′ north and south. The projection's ''x'' and ''y'' coordinates can be computed as : \begin x &= 2 R \left(\lambda - \lambda_0 \right) \sqrt \\ y &= R \sqrt \left(2 - \sqrt\right) \end where ''λ'' is the longitude, ''λ''0 is the central meridian, ''φ'' is the latitude, and ''R'' is the radius of the globe to be projected. Here, ''y'' assumes the sign of ''φ''.


See also

*
Max Eckert-Greifendorff Max Eckert (after 1934, Max Eckert-Greifendorff: 10 April 1868 in Chemnitz, Kingdom of Saxony – 26 December 1938, in Aachen) was a German geographer. Biography He received his education in Löbau and Berlin, and taught for some time at Löbau ...
*
List of map projections This is a summary of map projections that have articles of their own on Wikipedia or that are otherwise notable Notability is the property of being worthy of notice, having fame, or being considered to be of a high degree of interest, signif ...
*
Eckert IV projection The Eckert IV projection is an equal-area pseudocylindrical map projection. The length of the polar lines is half that of the equator, and lines of longitude are semiellipses, or portions of ellipses. It was first described by Max Eckert in 1 ...
*
Eckert VI projection The Eckert VI projection is an equal-area pseudocylindrical map projection. The length of polar line is half that of the equator, and lines of longitude are sinusoids. It was first described by Max Eckert in 1906 as one of a series of three p ...


References


External links


Eckert II at Mapthematicsradicalcartography.netCartographic Projection Procedures (Pdf) by Gerald I. Evenden
{{Map projections Map projections Equal-area projections