[PROJ] Big grid files

[Jack Riley - NOAA Federal]

I read in
https://proj.org/en/stable/specifications/geodetictiffgrids.html#general-description
that
files hosted on the CDN support Signed/Unsigned Int 16 and Int 32.  Might
this be expanded to include Int 8, given its support in GDAL>=3.7.0:
https://gdal.org/en/stable/development/rfc/rfc87_signed_int8.html

I'm working with a PROJ auxiliary database that includes a lot of large
transformation grids that scale to Int8 with sub-mm precision.


On Sun, Apr 27, 2025 at 8:43 AM Even Rouault via PROJ <proj at lists.osgeo.org>
wrote:

>
> Le 24/04/2025 à 21:51, Mike Taves via PROJ a écrit :
>
> There is Git Large File Storage (Git LFS), which has a limit of 2GB.
>
> Yes, but there are billing / bandwidth implications. I remember we had it
> enabled, but CI cloning typically exhausted the allowed free bandwidth.
>
> Javier, maybe you can try using gdal_translate -scale X X X X -ot UInt16
> -co COMPRESS=DEFLATE -co TILED=YES -co PREDICTOR=2 with the appropriate
> scaling values ?
>
> Or gdal_translate -co DISCARD_LSB=X -co COMPRESS=DEFLATE -co TILED=YES -co
> PREDICTOR=3  to nullify least signifcant bits of the mantissa.
>
>
>
> On Fri, 25 Apr 2025, 04:37 Javier Jimenez Shaw via PROJ, <
> proj at lists.osgeo.org> wrote:
>
>> Hi
>>
>> I am playing with the new American geoid model SGEOID2022
>>
>> After compressing with this command (can I do it better?)
>> gdal_translate sgeoid2022.tif sgcomp.tif -co COMPRESS=DEFLATE -co
>> TILED=YES -co PREDICTOR=3
>> I get a 110 MB file (and it is only one band. No velocities).
>>
>> GitHub has a limit of 100MB:
>>
>> https://docs.github.com/en/repositories/working-with-files/managing-large-files/about-large-files-on-github
>>
>> Just to let you know.
>>
>> Cheers,
>> Javier.
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>>
>
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