API Reference > imodeljs-common > Geometry > GeodeticDatumProps > ellipsoid ellipsoid ellipsoid: undefined | GeodeticEllipsoidProps The full definition of the geodetic ellipsoid associated to the datum. If undefined then the ellipsoidId must be used to fetch the definition from the dictionary, geographic coordinate system service or the backend Defined in core/common/src/geometry/GeodeticDatum.ts Line 472 Last Updated: 12 June, 2024