[Qgis-user] NTv2-transformation: different output values in QGIS and GDAL

[andy]

Hi,
I'm doing NTv2-transformation, using this gsb file:
https://web.archive.org/web/20201018143532/https://provincia.agrigento.sitr.it/scaricabili/NTv2/ItalyED50toWGS84_NTV2_GN.gsb

I have copied it in "C:\OSGeo4W\share\proj" and I have defined this custom
projection:
+proj=utm +zone=33 +ellps=intl +nadgrids=ItalyED50toWGS84_NTV2_GN.gsb
+units=m +no_defs +type=crs

If I test it in QGIS, in the custom CRS window, using lon=13 and lat=38, I
have in output:
324388.7743
4207772.1972

If I do the same in gdal, running

gdaltransform --debug ON -s_srs EPSG:4326 -t_srs "+proj=utm +zone=33
+ellps=intl +nadgrids=C:\OSGeo4W\share\proj\ItalyED50toWGS84_NTV2_GN.gsb
+units=m +no_defs +type=crs"

I get
324454.613619553
4207894.92605038

Why do I have these differences? Am I doing something wrong?

I'm using QGIS 3.28.2-Firenze and GDAL 3.6.2, released 2023/01/02, in
Windows 11.

Thank you,

Andrea

-- 
___________________

Andrea Borruso
website: https://medium.com/tantotanto
38° 7' 48" N, 13° 21' 9" E, EPSG:4326
___________________

"cercare e saper riconoscere chi e cosa,
 in mezzo all’inferno, non è inferno,
e farlo durare, e dargli spazio"

Italo Calvino
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