Natural Earth projection

Natural Earth projection of the world.

The natural Earth projection with Tissot's indicatrix of deformation

The Natural Earth projection is a pseudocylindrical map projection designed by Tom Patterson and introduced in 2012. It is neither conformal nor equal-area, but a compromise between the two.

It was designed in Flex Projector, a specialized software application that offers a graphical approach for the creation of new projections.

Definition

The natural Earth is defined by the following formulas:

${\begin{aligned}x&=l(\varphi )\times \lambda ,\\y&=d(\varphi ),\end{aligned}}$,

where

• $x\in [-2.73539,2.73539]$ and $y\in [-1.42239,1.42239]$ are the Cartesian coordinates;
• $\lambda \in [-\pi ,\pi ]$ is the longitude from the central meridian in radians;
• $\varphi \in [-\pi /2,\pi /2]$is the latitude in radians;
• $l(\varphi )$ is the length of the parallel at latitude $\varphi$;
• $d(\varphi )$ is the distance of the parallel from the equator at latitude $\varphi$.

$l(\varphi )$ and $d(\varphi )$ are given as polynomials:

$${\begin{aligned}l(\varphi )&=0.870700-0.131979\times \varphi ^{2}-0.013791\times \varphi ^{4}+0.003971\times \varphi ^{10}-0.001529\times \varphi ^{12},\\d(\varphi )&=\varphi \times (1.007226+0.015085\times \varphi ^{2}-0.044475\times \varphi ^{6}+0.028874\times \varphi ^{8}-0.005916\times \varphi ^{10}).\end{aligned}}$$

In the original definition of the projection, planar coordinates were lineally interpolated from a table of 19 latitudes and then multiplied by other factors. The authors of the projection later provided a polynomial representation that closely matches the original but improves smoothness at the "corners".

See also

• Robinson projection
• Winkel tripel projection
• Kavrayskiy VII
• Equal Earth projection