[Proj] Cct, proj_create_crs_to_crs and towgs84 parameters

Kristian Evers kreve at sdfe.dk
Mon Feb 12 04:16:55 EST 2018

Hi Olli,

Thanks for reporting this. You assume correct. The issue has already been reported and mostly fixed. See the discussion here: https://github.com/OSGeo/proj.4/issues/783.

This should be fixed in RC3.


Fra: proj-bounces at lists.maptools.org [mailto:proj-bounces at lists.maptools.org] På vegne af Olli Räisä
Sendt: 12. februar 2018 09:36
Til: proj at lists.maptools.org
Emne: [Proj] Cct, proj_create_crs_to_crs and towgs84 parameters


Proj-5.0.0RC2 cct outputs appear to differ from cs2cs outputs, when a coordinate reference system has non-zero towgs84 parameters.

An example:

bin\cs2cs +init=epsg:2393 +to +init=epsg:3879
3500000 6650000 0
25611546.42     6651551.63 25.30

bin\cct -t0 +proj=pipeline +step +init=epsg:2393 +inv +step +init=epsg:3879
3500000 6650000 0
25611608.8193   6651462.4308      340.2153        0.0000

Looking at proj_create_crs_to_crs function code, I assumed that these commands produce the same results (within some tolerance).

Olli Räisä

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