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Modeling the Earth

Represent the shape and size of the Earth; represent ellipsoids; convert between parameters


wgs84Ellipsoid Reference ellipsoid for World Geodetic System 1984
earthRadius Mean radius of planet Earth
rcurve Ellipsoidal radii of curvature
rsphere Radii of auxiliary spheres
geocentricLatitude Convert geodetic to geocentric latitude
parametricLatitude Convert geodetic to parametric latitude
geodeticLatitudeFromGeocentric Convert geocentric to geodetic latitude
geodeticLatitudeFromParametric Convert parametric to geodetic latitude
axes2ecc Eccentricity of ellipse from axes lengths
majaxis Semimajor axis of ellipse
minaxis Semiminor axis of ellipse
ecc2flat Flattening of ellipse from eccentricity
flat2ecc Eccentricity of ellipse from flattening
ecc2n Third flattening of ellipse from eccentricity
n2ecc Eccentricity of ellipse from third flattening


oblateSpheroid Oblate ellipsoid of revolution
referenceEllipsoid Reference ellipsoid
referenceSphere Reference sphere
map.geodesy.AuthalicLatitudeConverter Convert between geodetic and authalic latitudes
map.geodesy.ConformalLatitudeConverter Convert between geodetic and conformal latitudes
map.geodesy.IsometricLatitudeConverter Convert between geodetic and isometric latitudes
map.geodesy.RectifyingLatitudeConverter Convert between geodetic and rectifying latitudes


Spheres, Spheroids, and Geoids

The shape of the Earth can be approximated as a perfect sphere, an oblate ellipsoid, or a geoid.

Geoid and Ellipsoid

The geoid shape of the Earth includes approximations for flattening and localized variations in height.

Reference Spheroids

A reference spheroid is a model of a roughly-spherical astronomical body.

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