Albers projection

Albers projection of the world with standard parallels 20°N and 50°N.

The Albers equal-area conic projection, or Albers projection (named after Heinrich C. Albers), is a conic, equal area map projection that uses two standard parallels. Although scale and shape are not preserved, distortion is minimal between the standard parallels.

The Albers projection is one of the standard projections for British Columbia,^[1] and is the sole standard projection used by the government of Yukon.^[2] It is also used by the United States Geological Survey and the United States Census Bureau.^[3]

Snyder^[4] (Section 14) describes generating formulae for the projection, as well as the projection's characteristics. Coordinates from a spherical datum can be transformed into Albers equal-area conic projection coordinates with the following formulas,^[5] where λ is the longitude, λ₀ the reference longitude, φ the latitude, φ₀ the reference latitude and φ₁ and φ₂ the standard parallels:

$x = \rho \sin\theta$

$y = \rho_0 - \rho \cos\theta$

where

$n = {\tfrac12} (\sin\varphi_1+\sin\varphi_2)$

$\theta = n(\lambda - \lambda_0)$

$C = \cos^2 \varphi_1 + 2 n \sin \varphi_1$

$\rho = \frac{\sqrt{C - 2 n \sin \varphi}}{n}$

$\rho_0 = \frac{\sqrt{C - 2 n \sin \varphi_0}}{n}$

See also

• List of map projections

References

1. British Columbia
2. "Support & Info: Common Questions". Geomatics Yukon. Government of Yukon. Retrieved 15 October 2014.
3. "Projection Reference". Bill Rankin. Archived from the original on 25 April 2009. Retrieved 2009-03-31.
4. Snyder, John P. (1987). Map Projections – A Working Manual. U.S. Geological Survey Professional Paper 1395. United States Government Printing Office, Washington, D.C. This paper can be downloaded from USGS pages.
5. Weisstein, Eric. "Albers Equal-area Conic Projection". Wolfram MathWorld. Wolfram Research. Retrieved 2013-05-04.

External links

• Mathworld's page on the Albers projection
• Table of examples and properties of all common projections, from radicalcartography.net
• Yukon Albers Projection
• An interactive Java Applet to study the metric deformations of the Albers Projection.