Le 24/02/2026 à 14:00, Andrea Giudiceandrea via PROJ a écrit :
Il 24/02/2026 13:23, Andrea Giudiceandrea ha scritto:
Thank you very much, Even. Your explanation clarifies all my doubts!
Actually, not exactly all...
I wonder why In QGIS the listed transformations available for
EPSG:23033 -> EPSG:3065 are only 2 (1 grid, 1 ballpark, corresponding
to projinfo without "--grid-check discard_missing") instead of the 6
(5 Helmert, 1 ballpark) listed by projinfo with "--grid-check
discard_missing" or a union of both (1 grid shift, 5 Helmert and 1
ballpark).
This creates a discrepancy, making QGIS use a ballpark transformation
whereas a better one could be used.
Maybe it would be useful if QGIS could list and let the user choose
among all the available transformations, wouldn't it?
This is a case where one could argue which one is the best between the
ballpark ED50 -> IGM95 or going through WGS 84 by using a likely poorly
conditionned Helmert transformation. Both results are right and wrong to
some accuracy requirements...
Why IGM is still not releasing freely their grids ? (I remember doing
them some education in Firenze in 2022 ...)
Even
--
http://www.spatialys.com
My software is free, but my time generally not.
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