is an option for GeoGraphics that specifies the reference body or model for it for the purposes of geodetic computations and map drawing.


  • The following settings can be used:
  • Automaticuse the "ITRF00" datum for the Earth
    "datum"any of the datums in GeodesyData["Datum"]
    "ellipsoid"any of GeodesyData["ReferenceEllipsoid"]
    {a,b}an explicit ellipsoid with semiaxes ab
    ra sphere of radius r
    entitya planet or planetary moon Entity object
  • The semiaxes lengths a, b in GeoModel{a,b} and the radius r in GeoModelr can be given either as numbers in meters or Quantity lengths.


open allclose all

Basic Examples  (2)

Use the default (ellipsoidal) model of the Earth, where geodesics do not close:

Use a spherical model of the Earth, where geodesics close:

Use Mars as a reference model:

Use the Moon:

Applications  (1)

Store the coordinates/sizes of the lunar maria:

Plot the maria together with their names (as tooltips):

Properties & Relations  (2)

Show unclosed geodesics, which are one consequence of the nonsphericity of the Earth:

Compare with a spherical model:

Large disks accumulating around the antipodal point, using a spherical model of the Earth:

The default reference model is an ellipsoid:

Introduced in 2014