[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
bergermann partner

Beratende Ingenieure
für erneuerbare Energie

Stuttgart . Berlin . New York
São Paulo . Shanghai . Paris

sbp sonne gmbh

Markus Balz Dipl.Ing. (FH)
Andreas Keil Dipl.Ing.

Schwabstrasse 43
70197 Stuttgart
Telefon +49 (711) 648 71-0

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