Le 16/01/2024 à 11:59, andy via QGIS-User a écrit :
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
Did you try with the full path
+nadgrids=C:\OSGeo4W\share\proj\ItalyED50toWGS84_NTV2_GN.gsb ?
If I do that (well on Linux: "+proj=utm +zone=33 +ellps=intl
+nadgrids=/home/even/qgis/qgis/build_ubuntu2204/ItalyED50toWGS84_NTV2_GN.gsb
+units=m +no_defs"), I do get the correct result 324454.6136
4207894.9261 in QGIS (master)
But, what is the history of this "ghost" grid that requires fetching it
from web.archive.org ? Has it had some official status, and could it be
provided under an open data license ? If so, it would be great if
Italian authorities could register to IOGP/EPSG this grid for ED50 ->
WGS 84 for Italy... Then we could ship it in PROJ-data.
But I remember complicated discussion at FOSS4G Firenze with the guys
from the geodetic authority (https://www.igmi.org).... Not sure if that
has lead to anywhere.
Even
--
http://www.spatialys.com
My software is free, but my time generally not.
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