[PROJ] How to apply Helmert trafo
Fabian Gross
F.Gross at sbp.de
Fri Jun 14 06:40:47 PDT 2019
Dear proj-members,
I would like to apply a Helmert trafo as part of a datum shift.
The example follows the EPSG geomatics guidance 7/2 (report 373-7-2):
>From WGS72 (4984) -> WGS84 (4978).
There are 2 issues:
1. How to apply Helmert-Trafo? I.e.
with or
without the push/pop of the ellipsoidal height.
Only if it is not pushed/popped do the values fit to the reference and the
direct/naive implementation of Helmert.
2. The scale parameters in the example (0.219) and the EPSG catalogue of
pyproj (0.2263) do not agree.
The attached file has the test case.
Kind regards
Fabian Gross
Telefon +49 (711) 648 71-995
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