By implication, ellipsoidal heights (h) cannot be captured in a vertical coordinate reference system. Ellipsoidal heights cannot exist independently, but only as inseparable part of a 3D coordinate tuple defined in a geographic 3D coordinate reference system. However GeoAPI does not enforce this rule. Some applications may relax this rule and accept ellipsoidal heights in the following context:
As a transient state while parsing Well Known Text, or any other format based on legacy specifications where ellipsoidal heights were allowed as an independent axis.
As short-lived objects to be passed or returned by methods enforcing type safety, for example
Other cases at implementor convenience. However implementors are encouraged to assemble the full 3D CRS as soon as they can.
|Used with CS type(s)|
getCoordinateSystem@UML(identifier="coordinateSystem", obligation=MANDATORY, specification=ISO_19111) VerticalCS getCoordinateSystem()Returns the coordinate system, which must be vertical.
getDatumReturns the datum, which must be vertical.