Bottomley projection

The Bottomley map projection is a pseudoconical equal area map projection[1] defined as: where and φ is the latitude, λ is the longitude from the central meridian, and φ1 is the given parallel of the projection which determines its shape, all in radians.

The inverse projection is then given by: where Parallels (i.e. lines of latitude) are concentric elliptical arcs of constant eccentricity equal to cos φ1, centred on the North Pole.

For larger values of φ1, it produces a heart shape.

[2] It was introduced by Henry Bottomley as an alternative to the Bonne projection to reduce the extent of extreme distortion at the edges and give a more satisfying overall shape.

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