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Trying to apply a grid shift file to GeoServer. Have looked at the documentation but all it seems to say is to put the files in the user_projections, which I've done.

I'm trying to use OSTN15_NTv2_OSGBtoETRS.gsb to convert EPSG:27700 to EPSG:3857. I've downloaded the NTv2 grid files and added to the user_projections folder, however it doesn't seem to have any affect when testing in the Reprojection console.

How do I 'make' GeoServer use the more accurate grid shift?

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All I can say is it works on my machine - I added ISTN02_NTv2.gsb to data/user_projections. Restarted GeoServer (not sure if it is necessary but never hurts) and now I see this in the reprojection tool.

enter image description here

Update

I downloaded the OSTN15_NTv2_OSGBtoETRS.gsb file and added it to data/user_projections too. Now when I look at the transformation in the reprojection tool I see:

enter image description here

Are you sure that the tomcat user can read the file?

➜  user_projections  ls -l
total 68856
-rw-r--r-- 1 tomcat8 tomcat8    12905 Jan 13  2017 epsg.properties
-rw-r--r-- 1 root    root    15240384 Feb 25  2019 OSTN02_NTv2.gsb
-rw-r--r-- 1 root    root         432 Feb 25  2019 OSTN02_NTv2_Header.txt
-rw-r--r-- 1 root    root    40005491 Feb 25  2019 OSTN02_NTv2.txt
-rw-r--r-- 1 root    root    15240384 Feb 25 17:13 OSTN15_NTv2_OSGBtoETRS.gsb

(Oh, and you don't need to restart GeoServer for it to take effect)

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  • Does it make a difference as I'm trying to use the OSTN15_NTv2_OSGBtoETRS.gsb and not the OSTN02_NTv2.gsb in your example @Ian?
    – Rob
    Feb 25, 2021 at 12:14
  • Just tried with the OSTN02_NTv2.gsb file and I get same results as you @Ian, so am I asking the wrong question? Trying to use the newer more accurate grid shift from the OS
    – Rob
    Feb 25, 2021 at 12:32
  • Thanks for your help @Ian, downloaded the same file you linked to (in case I had a duff version), put both files (OSTN02 & OSTN15) in folder with same permissions, console references OSTN02 version. Remove the OSTN02 file and doesn't pick up the OSTN15. Anything else you can think to check?
    – Rob
    Feb 25, 2021 at 20:11
  • can you check the log and see if there is anything there that indicates it can't find the file, a search for 'NTv2' should find them
    – Ian Turton
    Feb 26, 2021 at 9:34
  • Nothing in the logs @Ian. Absolutely baffled 😖.
    – Rob
    Feb 26, 2021 at 16:20

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