[gdal-dev] GDAL 3 and PROJ 6

[Juan Pedro Pérez Alcántara]

Hi everyone,

I maintain a set of Docker containers of PostGIS and currently I'm working
on a new release with updated version of the stack, which include PROJ 6,
GDAL 3, PostgreSQL 11.5, and PostGIS 2.5.3. I know PROJ 6 is a game
changer, and all the work I've done in the past configuring PROJ 4 to my
country (Spain) transformations with GSB grids might have been deprecated.
It appears so! Hopefully, after attempting a lot of things, I was able to
make PROJ 6 work nicely with the GSB by providing a resource epsg file.

My hopes were that, once PROJ 6 was in place, GDAL 3 would make use of it
for gdaltransform, but somehow GDAL is not playing nicely with PROJ 6 and
transformations are not using the grids. If someone can shed some light
regarding this issues, I'll be most grateful:

- what is the relation between GDAL 3 and PROJ 6? I mean, if cs2cs is using
the grid to transform, shouldn't GDAL rely on PROJ for reprojection and do
it well too?

- if GDAL has to be configured independently, what's the proper way to
attach a grid to a EPSG code so reprojections using the epsg:XXXXX syntax
would work with the grid?

Many thanks in advance for any help you can provide me, I'm pretty lost!

---

Juan Pedro Pérez Alcántara

jp.perez.alcantara at gmail.com
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