Modeling the Earth
Represent the shape and size of the Earth; represent
ellipsoids; convert between parameters
|Geographic coordinate reference system|
|Reference ellipsoid for World Geodetic System 1984|
|Geoid height from Earth Gravitational Model 1996 (EGM96)|
|Mean radius of planet Earth|
|Ellipsoidal radii of curvature|
|Radii of auxiliary spheres|
|Eccentricity of ellipse from axes lengths|
|Semimajor axis of ellipse|
|Semiminor axis of ellipse|
|Flattening of ellipse from eccentricity|
|Eccentricity of ellipse from flattening|
|Third flattening of ellipse from eccentricity|
|Eccentricity of ellipse from third flattening|
The Shape of the Earth
The Earth can be modeled with increasing precision as a perfect sphere, an oblate
spheroid, an ellipsoid, or a geoid.
A reference spheroid is a model of a roughly-spherical astronomical body with a
simplified geometry, such as a sphere with uniform radius or a standard ellipsoid.
Work with Reference Spheroids
Use reference spheroids to create map projections, to calculate curves and areas on
the surface of a spheroid, and to transform 3-D geodetic coordinates.