[PROJ] Wrong transformation in NL?

[Javier Jimenez Shaw]

Even anyway answered with a bugfix.

ETRS89 now has more than 40 new members, from many European countries. The
change is a free days old in EPSG.
Yes, the 40m difference is the geoid height in Europe.

On Sun, 22 Feb 2026, 02:22 Greg Troxel via PROJ, <proj at lists.osgeo.org>
wrote:

> Javier Jimenez Shaw via PROJ <proj at lists.osgeo.org> writes:
>
> > Just testing something else, I tried this transformation to go test that
> > the grids are properly used.
> > In master this seems to be wrong
> >
> > echo 52 5 0 | PROJ_DATA=data/ PROJ_NETWORK=ON ./bin/cs2cs EPSG:4326+3855
> > EPSG:7415
> > 128410.09 445806.51 -43.41
> >
> > ./bin/cs2cs
> > Rel. 9.8.0, March 2nd, 2026
> >
> > While in the native cs2cs in Ubuntu 24.04 makes more sense. Just 20 cm
> > difference between EGM2008 and NAP height.
> >
> > echo 52 5 0 | PROJ_NETWORK=ON cs2cs EPSG:4326+3855 EPSG:7415
> > 128410.10 445806.50 0.20
> >
> > cs2cs
> > Rel. 9.4.0, March 1st, 2024
>
> Separately from what's being viewed as a bug, etc. WGS84 is an ensemble
> with 2m error just from the ensemble.  But I would then expect any wrong
> answers people are complaining about to be within 2m or so.
>
> Am I reading this right that 0 m in EGM2008 is 20 cm in NAP?  (I get it
> that this is super close and we expect close since they are both trying
> to match mean sea level, with the caveat that mean sea level is a
> difficult concept, with EGM2008 tied to some global MSL and NAP to some
> measured sea level over some period at one(?) tide gauge.)
>
> What I'm boggled by is -43.41 m.  That feels like a geoid height, not a
> difference it orthometric datum reference surface.  Which suggests that
> something is more seriously wrong.
>
> > If my tests are correct, and I had to guess, I would say it is a
> > consequence of the new ETRS89 ensemble.
>
> Do you mean "ETRS89 recently got a new member ETRF2020"?  Without really
> understanding, I would expect coordinate differences between ETRF2000
> and ETRF2020 to be on the order of one to a few cm, and that this is not
> able to explain a 1m delta, let along 43m.
>
> (Also, I think this discussion is all about NAP and not about EVRF at
> all.)
> _______________________________________________
> PROJ mailing list
> PROJ at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/proj
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/proj/attachments/20260222/44cfb192/attachment.htm>