hyperelliptical

Parameters: alpha, gamma > 1, k >> 0

Classifications

pseudocylindric
equal-area

Graticule

Meridians: Hyperelliptical curves.
Parallels: Straight parallel lines, spaced so as to make the projection equal-area. Perpendicular to the central meridian.
Poles: Points or lines depending on parameterization.
Symmetry: About the central meridian and the equator.

Distortion

Dependent on parameterization. In the default parameterization as recommended by Tobler, the projection has no distortion only at 37°33′N/S on the central meridian.

Parameters

Parameterization for this projection is finicky to use and hard to describe the effects of.
The three parameters are alpha, gamma, and k. Combinations that do not result in a proper projection will be rejected by Geocart. Any usable combination results in an equal-area map.

Similar projections

Degenerate cases of the hyperelliptical include Molleweide (alpha = 0, gamma = 1.27323394, k = 2) and Collignon (alpha = 0, gamma = 2, k = 1).

Origin

Waldo Tobler, 1973.

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