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The Bottomley map projection is a pseudoconical equal area map projection defined as: :x = \frac, \qquad y = \frac - \rho \cos E \, where :\rho = \frac - \varphi, \qquad E = \frac and ''φ'' is the latitude, ''λ'' is the longitude from the central meridian, and ''φ''1 is the given parallel of the projection which determines its shape, all in radians. The inverse projection is then given by: :\begin\varphi &= \frac - \rho \\ \lambda &=\frac \end where :\rho = \sqrt, \qquad E= \tan^\left(\frac\right). Parallels (i.e. lines of latitude) are concentric elliptical arcs of constant eccentricity equal to cos ''φ''1, centred on the
north pole The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's rotation, Earth's axis of rotation meets its surface. It is called the True North Pole to distingu ...
. On the central
meridian Meridian or a meridian line (from Latin ''meridies'' via Old French ''meridiane'', meaning “midday”) may refer to Science * Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon * ...
, shapes are not distorted, but elsewhere they are. Different projections can be produced by altering the eccentricity of the arcs, making it vary between the
sinusoidal projection The sinusoidal projection is a pseudocylindrical equal-area map projection, sometimes called the Sanson–Flamsteed or the Mercator equal-area projection. Jean Cossin of Dieppe was one of the first mapmakers to use the sinusoidal, appearing ...
and the
Werner projection The Werner projection is a pseudoconic equal-area map projection sometimes called the Stab-Werner or Stabius-Werner projection. Like other heart-shaped projections, it is also categorized as cordiform. ''Stab-Werner'' refers to two originators: ...
. For larger values of ''φ''1, it produces a heart shape.Compare Map Projections
/ref> It was introduced by Henry Bottomley as an alternative to the
Bonne projection The Bonne projection is a pseudoconical equal-area map projection, sometimes called a dépôt de la guerre, modified Flamsteed, or a Sylvanus projection. Although named after Rigobert Bonne (1727–1795), the projection was in use prior to his ...
to reduce the extent of extreme distortion at the edges and give a more satisfying overall shape.


See also

*
List of map projections This is a summary of map projections that have articles of their own on Wikipedia or that are otherwise notable Notability is the property of being worthy of notice, having fame, or being considered to be of a high degree of interest, signif ...


References


External links


Cybergeo article
''Between the Sinusoidal projection and the Werner: an alternative to the Bonne (Une alternative à la projection cartographique de Bonne)'', Henry Bottomley, 2003 Map projections Equal-area projections {{Cartography-stub