Simon,
We do not currently redistribute anything from the separate
*proj-data* bundle, only the basic set of files that end up in
*.../share* from a PROJ make/install (*proj.db* and about 15 others,
e.g. *nad83*)
Well, hopefully you don't need to do accurate datum transformations ;-)
This perhaps dates from when the full set of files was included in the
main bundle, but that is before my time, and obviously they have been
split out by you into a separate bundle for quite some time now,
presumably because of their size.
yes
We have never had any issues (that we know of!) with failing to
interpret client data files, so evidently PROJ manages quite happily
without the additional files from the *proj-data* bundle but perhaps
we should be redistributing those as well?
PROJ will never error out about missing grid files by default, unless
you set PROJ_ONLY_BEST_DEFAULT=YES ( Cf
https://proj.org/en/9.3/apps/cs2cs.html#index-0) , or equivalent setting
through proj.ini or the API (accessible
from OGRCoordinateTransformationOptions::SetOnlyBest () in GDAL:
https://gdal.org/doxygen/structOGRCoordinateTransformationOptions.html#a77fffa9f5f421c21c9104f6ba03885a5
, or OCTCoordinateTransformationOptionsSetOnlyBest():
https://gdal.org/api/ogr_srs_api.html#_CPPv445OCTCoordinateTransformationOptionsSetOnlyBest35OGRCoordinateTransformationOptionsHb)
.
If a grid is missing, in the default mode (only_best=no)n PROJ will
fallback to whatever other less precise transformations it has, or do a
"ballpark" transformation (no-op) in the worse case, which can be off by
several tens of meters or more.
If so, do we just combine the two sets of files into the same
*PROJ_DATA* directory?
Yes, you can have proj.db and the grids in the same directory. Or have
different directories and mention them in PROJ_DATA using ';' separator
on Windows, or ':' on Unix-like systems. (same convention as PATH). Cf
https://proj.org/en/9.3/usage/environmentvars.html#envvar-PROJ_DATA
Forgive me if there is documentation on this specific topic which I
have missed.
Finally, is the latest *proj-data-1.16* compatible with PROJ 9.3.0
(which we have frozen on for our latest dependencies update) or must
we use the previous 1.14 from June? ...
Yes, that should work. Only new content has been added
and what happened to 1.15? :)
proj-data 1.15 was released together with 9.3.0, and proj-data 1.14 with
proj 9.2.1
Even
--
http://www.spatialys.com
My software is free, but my time generally not.
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