helmert_parameters¶

geodetic_engine.geodesy.utils.helmert_parameters(operation)[source]¶

Read a plain Helmert’s parameters, normalised to position vector.

Parameters:: operation (CoordinateOperation) – A single coordinate operation.
Return type:: HelmertParameters | None
Returns:: The parameters in SI units, or None if the operation is not a plain Helmert. Molodensky-Badekas, time-dependent, time-specific and full matrix variants all return None, because none of them is the linearised affine map about the geocentre that compose() assumes.

Example

>>> helmert_parameters(CoordinateOperation.from_authority("EPSG", 1147))
HelmertParameters(tx=-1.51, ...)