[MapServer-users] Trying to get the right transformation with Mapserver 8.0.0 + PROJ 9.1.0

[Wouter Visscher]

Hi,

I'm struggling a bit with Mapserver (8.0.0) + PROJ (9.1.0) getting it to
use the right transformation (RDTRANS2018) rules.

I have a (Docker) environment with
- PROJ 9.1.0
- GDAL 3.5.2
- Mapserver 8.0.0 (branch-8-0)

When I run cs2cs (PROJ) the output is correct (in order words what I
expect) going from EPSG:28992 -> EPSG:4258.
With PROJ_DEBUG on I can verify that is calling the right tif
(nl_nsgi_rdtrans2018.tif in this case)
Moving up the chain by using GDAL (ogr2ogr GPKG EPSG:28992 -> GPKG
EPSG:4258) I get the same correct result.

But putting it all together with Mapserver I'm not seeing the same result
and I'm getting results +100m from where they should be.
The strange thing is when I use EPSG:25831 (ETRS89 / UTM zone 31N, in
meters) instead of EPSG:4258 (ETRS89, degree) the results are correctly
translated. (also using the nl_nsgi_rdtrans2018.tif when called with cs2cs)

Mapserver also seems to use the correct PROJ 9.1.0, when I alter PROJ_DATA
or remove the proj.db it says it's missing them.
Also using different data sources like GPKG, FGB, and so on doesn't seem to
change this behaviour.

Does anyone know what could be causing this or advice on how to further
investigate the issue?

Regards,
Wouter
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