Van der Grinten projection

Van der Grinten projection of the world.

The van der Grinten projection is a compromise map projection, which means that it is neither equal-area nor conformal. Unlike perspective projections, the van der Grinten projection is an arbitrary geometric construction on the plane. Van der Grinten projects the entire Earth into a circle. It largely preserves the familiar shapes of the Mercator projection while modestly reducing Mercator's distortion. Polar regions are subject to extreme distortion.^[1]

History

Alphons J. van der Grinten invented the projection in 1898 and received US patent #751,226 for it and three others in 1904.^[2] The National Geographic Society adopted the projection for their reference maps of the world in 1922, raising its visibility and stimulating its adoption elsewhere. In 1988, National Geographic replaced the van der Grinten projection with the Robinson projection.^[1]

Geometric construction

The geometric construction given by van der Grinten can be written algebraically:^[3]

{\begin{aligned}x&={\frac {\pm \pi \left(A\left(G-P^{2}\right)+{\sqrt {A^{2}\left(G-P^{2}\right)^{2}-\left(P^{2}+A^{2}\right)\left(G^{2}-P^{2}\right)}}\right)}{P^{2}+A^{2}}}\\[5px]y&={\frac {\pm \pi \left(PQ-A{\sqrt {\left(A^{2}+1\right)\left(P^{2}+A^{2}\right)-Q^{2}}}\right)}{P^{2}+A^{2}}}\end{aligned}}

where x takes the sign of λ − λ₀, y takes the sign of φ and

{\begin{aligned}A&={\frac {1}{2}}\left|{\frac {\pi }{\lambda -\lambda _{0}}}-{\frac {\lambda -\lambda _{0}}{\pi }}\right|\\[5px]G&={\frac {\cos \theta }{\sin \theta +\cos \theta -1}}\\[5px]P&=G\left({\frac {2}{\sin \theta }}-1\right)\\[5px]\theta &=\arcsin \left|{\frac {2\varphi }{\pi }}\right|\\[5px]Q&=A^{2}+G\end{aligned}}

Where φ = 0,

{\begin{aligned}x&=\left(\lambda -\lambda _{0}\right)\\y&=0\end{aligned}}

Similarly, if λ = λ₀ or φ = ± $π$ /2, then

{\begin{aligned}x&=0\\y&=\pm \pi \tan {\frac {\theta }{2}}\end{aligned}}

In all cases, φ is the latitude, λ is the longitude, and λ₀ is the central meridian of the projection.

References

1 2 Flattening the Earth: Two Thousand Years of Map Projections, John P. Snyder, 1993, pp.258-262, ISBN 0-226-76747-7.
↑ A Bibliography of Map Projections, John P. Snyder and Harry Steward, 1989, p. 94, US Geological Survey Bulletin 1856.
↑ Map Projections - A Working Manual, USGS Professional Paper 1395, John P. Snyder, 1987, pp. 239-242.

Bibliography

"Projections by Van der Grinten, and variations".

External links

Map projection

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List
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By surface

Cylindrical

Mercator-conformal	Gauss–Krüger Transverse Mercator

Equal-area	Balthasart Behrmann Gall–Peters Hobo–Dyer Lambert Smyth equal-surface Trystan Edwards

Cassini Central Equirectangular Gall stereographic Miller Space-oblique Mercator Web Mercator

General perspective	Gnomonic Orthographic Stereographic

Equidistant Lambert equal-area

Bonne	Sinusoidal Werner

Bottomley	Sinusoidal Werner

Cylindrical	Balthasart Behrmann Gall–Peters Hobo–Dyer Lambert cylindrical equal-area Smyth equal-surface Trystan Edwards

Tobler hyperelliptical	Collignon Mollweide

Albers Briesemeister Eckert II Eckert IV Eckert VI Hammer Lambert azimuthal equal-area Quadrilateralized spherical cube

Equidistant in
some aspect

Gnomonic

Gnomonic

Loxodromic

Retroazimuthal
(Mecca or Qibla)

Planar	Gnomonic Orthographic Stereographic

Central cylindrical

Polyhedral

See also

Latitude Longitude Tissot's indicatrix

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