[GRASS-dev] PROJ 5 support in trunk

[Markus Metz]

On Thu, Mar 22, 2018 at 7:16 AM, Markus Neteler <neteler at osgeo.org> wrote:
>
> On Tue, Mar 20, 2018 at 8:04 PM, Markus Metz
> <markus.metz.giswork at gmail.com> wrote:
> > Hi all,
> >
> > I have added support for the new PROJ 5+ API in trunk, finished with
r72433.
>
> That's really great! First OSGeo project :-)
>
> It was a lot of work for you, thanks.

The work is not yet finished. The current implementation works but is ugly
and code in modules became less readable because of lots of ifdefs for
PROJ4 or PROJ5. I am now testing a new GRASS API as interface to PROJ4/5
that would allow to remove these ifdefs in modules. The old GRASS API as
well as the standard PROJ4 API will still be supported. The main difference
is that GRASS now uses for PROJ5 the new pipeline syntax which allows to
define more complex transformations. Forward/backward transformation will
also become easier by simply defining the direction. m.proj still needs to
be updated to support this new pipeline syntax with any number of steps as
input for proj_in.

>
> > This means, trunk is now using exclusively the new PROJ 5+ API if
available.
> >
> > This new PROJ 5 API is available e.g. in Debian testing.
> >
> > Please test!
> >
> > During testing, I discovered some dangerous naming conflicts in GRASS
and
> > PROJ4/PROJ5: internal functions start both in GRASS and PROJ with pj_
which
> > can lead to cryptic errors. Within GRASS, some but not all
> > projection-related functions start with GPJ_, this should be adopted for
> > those starting with pj_. Also the GRASS structure struct pj_info should
be
> > renamed to struct gpj_info.
>
> BTW: Also GDAL now comes with support for PROJ 5, see
> https://lists.osgeo.org/pipermail/gdal-dev/2018-March/048278.html

Nice!

Markus M
>
> markusN
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