Kavrayskiy VII projection

The projection is defined as

$${\displaystyle \begin{array}{cc}x& =\frac{3\lambda }{2}\sqrt{\frac{1}{3}-{\left(\frac{\phi }{\pi }\right)}^2}\\ y& =\phi \end{array}}$$

where ${\displaystyle \lambda }$ is the longitude, and ${\displaystyle \phi }$ is the latitude in radians.