[PROJ] [GRASS-dev] GRASS GIS + PROJ 6 + GDAL 2.5

[Even Rouault]

On vendredi 8 mars 2019 18:22:42 CET Markus Metz wrote:
> On Fri, Mar 8, 2019 at 5:56 PM Even Rouault <even.rouault at spatialys.com>
> 
> wrote:
> > On vendredi 8 mars 2019 17:01:57 CET Markus Metz wrote:
> > > My question is, what should GRASS do with a SRS without proj string? The
> > > best answer is probably: use WKT instead of a proj string. But most of
> 
> the
> 
> > > GRASS code uses (for historical reasons) some form of proj syntax, also
> 
> to
> 
> > > store projection info for a GRASS location. If there is no proj string,
> > > GRASS thinks there is no SRS and falls back to a generic xy system
> 
> which is
> 
> > > not always correct.
> > 
> > The WKT will not help here. You will be able to get here, but you won't be
> > able to do coordinate transformation with it. This is just that this EPSG
> > method is not implemented or mapped to a PROJ projection method
> 
> I understand that coordinate transformation with PROJ will not be possible.
> But having a valid SRS definition would at least allow to compare two
> spatial references, i.e. OSRIsSame() should work. Having a valid SRS
> instead of dumping it would also help if the corresponding PROJ method
> becomes implemented in the future. That's why I am wondering about an
> alternative to the current proj-like projection information in GRASS.

Yes, for having a reference SRS definition, you can use the WKT export. By 
"useful", I meant being able to do coordinate transformation.
To compare SRS for equality, rather than using full string comparison, I'd 
suggest using proj_is_equivalent_to() which has a few options for different 
levels of equality.

Even

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