HI, I found the solution. To make everything work, you also need to write the parameters of the 2 systems you want to convert using grid shift (in the epsg_operations.properties file) before and after including the gsb file.
This is an example: 3003,3857=CONCAT_MT[INVERSE_MT[PARAM_MT["Transverse_Mercator",\ PARAMETER["semi_major", 6378388.0],\ PARAMETER["semi_minor", 6356911.9461279465],\ PARAMETER["central_meridian", 9.0],\ PARAMETER["latitude_of_origin", 0.0],\ PARAMETER["scale_factor", 0.9996],\ PARAMETER["false_easting", 1500000.0],\ PARAMETER["false_northing", 0.0]]],\ PARAM_MT["NTv2", PARAMETER["Latitude and longitude difference file", "NadRoma40.gsb"]],\ PARAM_MT["Popular Visualisation Pseudo Mercator",\ PARAMETER["semi_major", 6378137.0],\ PARAMETER["semi_minor", 6378137.0],\ PARAMETER["latitude_of_origin", 0.0],\ PARAMETER["central_meridian", 0.0],\ PARAMETER["scale_factor", 1.0],\ PARAMETER["false_easting", 0.0],\ PARAMETER["false_northing", 0.0]]] Daniele Maggiolo Da: Daniele Maggiolo via Geoserver-users <geoserver-users@lists.sourceforge.net> Inviato: giovedì 2 novembre 2023 14:49 A: geoserver-users@lists.sourceforge.net Oggetto: [Geoserver-users] Problems adding Grid Shift Transform files HI, I tried to configure a grid shift as explained in this guide: https://docs.geoserver.org/latest/en/user/configuration/crshandling/coordtransforms.html#examples using a gsb file. In the epsg_operations.properties file (inside user_projection) I wrote the following line: 3857,3003=PARAM_MT["NTv2",PARAMETER["Latitude and longitude difference file", "NadRoma40.gsb"]] and I put the NadRoma40.gsb file inside the same folder (file verified with other applications and working correctly). Now when I try to reproject from 3857 to 3003 if I click on "Show transformation details" I see that GeoServer has implemented my configuration (it shows me exactly what I wrote in the epsg_operation file), but the conversion does not work correctly. The log tells me "Point (1306188.4848936629, 5743812.429289647) is not covered by 'NadRoma40.gsb' NTv2 grid, it will not be moved." but I am sure that the point is contained by the grid. I also tried using the gsd file described in your guide and trying the coordinates system in your guide, but nothing with that either. I'm currently testing everything on a GeoServer version 2.23.1 Daniele Maggiolo
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