[QGIS-Developer] Dealing with datum shift grids in QGIS

[Even Rouault]

Martin,

It seems you want to have a read at my yesterday-written RFC:
https://github.com/OSGeo/proj.4/pull/1149

Particularly the part concerning the database:
http://even.rouault.free.fr/proj_cpp_api/rfc-2.html#database

and the data/sql/ files mentionne at

http://even.rouault.free.fr/proj_cpp_api/rfc-2.html#impacted-files

> 
> My suggestions for Proj:
> 1. it should be possible to specify multiple data directories with
> PROJ_LIB env variable, so that it is possible to use grids also from
> user's home directory (not just the read-only system directory)

That's an interesting idea. Could you file a ticket to
https://github.com/OSGeo/proj.4/issues about that ?


> 2. there could be a database similar to datum_shift.csv [2] that would
> list well known datum shift grid files, so that QGIS does not need to
> maintain its database and just pull that information out of Proj -
> other projects could benefit from that as well.

Sounds very much like:

https://github.com/rouault/proj.4/blob/iso19111/data/sql/grid_alternatives.sql


It would be good if we could utlimately get rid of QGIS srs.db and just use 
the future PROJ proj.db that could be used by the whole PROJ/GDAL/QGIS stack


Even

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