The Quartic Authalic projection is an equal-area projection. Its scale is true along the Equator, constant along any parallel, and between any pair of parallels equidistant from the Equator. Its distortion is severe near the outer meridians at high latitudes, but less so than on the Sinusoidal projection. It is free of distortion along the Equator. This projection is not conformal or equidistant.
Quartic Authalic Projection
To convert Quartic Authalic coordinates, the following parameters have to be set: