[PROJ] Wrong transformation in NL?

[Even Rouault]

Analysis and fix in https://github.com/OSGeo/PROJ/pull/4676

Le 21/02/2026 à 19:31, Javier Jimenez Shaw via PROJ a écrit :
> Hi
>
> 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
>
> The first pipeline of the projinfo are ... the same? I don't understand
>
> PROJ_NETWORK=ON projinfo -s EPSG:4326+3855 -t EPSG:7415 -o proj --bbox 
> 5,52,5.1,52.1
> Candidate operations found: 2
> -------------------------------------
> Operation No. 1:
>
> unknown id, Inverse of WGS 84 to EGM2008 height (1) + Inverse of 
> ETRS89 to WGS 84 (1) + ETRS89 to NAP height (2) + Inverse of 
> Amersfoort to ETRS89 (9) + RD New, 2.002 m, Netherlands - onshore, 
> including Waddenzee, Dutch Wadden Islands and 12-mile offshore coastal 
> zone.
>
> PROJ string:
> +proj=pipeline
>   +step +proj=axisswap +order=2,1
>   +step +proj=unitconvert +xy_in=deg +xy_out=rad
>   +step +proj=vgridshift +grids=us_nga_egm08_25.tif +multiplier=1
>   +step +inv +proj=vgridshift +grids=nl_nsgi_nlgeo2018.tif +multiplier=1
>   +step +inv +proj=hgridshift +grids=nl_nsgi_rdtrans2018.tif
>   +step +proj=sterea +lat_0=52.1561605555556 +lon_0=5.38763888888889 
> +k=0.9999079
>         +x_0=155000 +y_0=463000 +ellps=bessel
>
> -------------------------------------
> Operation No. 2:
>
>
> PROJ_DATA=data/ PROJ_NETWORK=ON ./bin/projinfo -s EPSG:4326+3855 -t 
> EPSG:7415 -o proj --bbox 5,52,5.1,52.1
> Candidate operations found: 6
> -------------------------------------
> Operation No. 1:
>
> unknown id, Inverse of WGS 84 to EGM2008 height (1) + Inverse of 
> ETRS89-NLD [AGRS2010] to WGS 84 (1) + ETRS89-NLD [AGRS2010] to NAP 
> height (2) + Inverse of Amersfoort to ETRS89-NLD [AGRS2010] (9) + RD 
> New, 1.123 m, Netherlands - onshore and offshore.
>
> PROJ string:
> +proj=pipeline
>   +step +proj=axisswap +order=2,1
>   +step +proj=unitconvert +xy_in=deg +xy_out=rad
>   +step +proj=vgridshift +grids=us_nga_egm08_25.tif +multiplier=1
>   +step +inv +proj=vgridshift +grids=nl_nsgi_nlgeo2018.tif +multiplier=1
>   +step +inv +proj=hgridshift +grids=nl_nsgi_rdtrans2018.tif
>   +step +proj=sterea +lat_0=52.1561605555556 +lon_0=5.38763888888889 
> +k=0.9999079
>         +x_0=155000 +y_0=463000 +ellps=bessel
>
> -------------------------------------
> Operation No. 2:
>
> If my tests are correct, and I had to guess, I would say it is a 
> consequence of the new ETRS89 ensemble.
>
> Cheers,
> Javier.
>
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