[GRASS-dev] [GRASS-SVN] r56717 - grass/trunk/demolocation/PERMANENT

Hamish hamish_b at yahoo.com
Sat Jun 15 04:33:24 PDT 2013

Hamish wrote:
> > in the case of the demolocation PROJ_INFO file I think
> > it's enough to just craft it by hand to make it as it should
> > be.

> Well, then this should be followed by a test if "v.unpack"
> works with it. All problems arose while trying to transfer
> a country map (from NaturalEarth )into it which I prepared
> time ago in a different latlong location.

The v.unpack projection matching method is fundamentally flawed
and should not be trusted.

line 102:# check projection compatibility in a rather crappy way"

I designed the check and wrote that comment in the initial
checkin of r.unpack, but to be honest I never meant for those
*.pack modules to become a core part of GRASS, they were just
some quick scripts I threw together and put in addons svn in
case they'd be useful to someone.

To see why it is so bad you can go back to the extended fun QGIS
and Maciek both had with epsg numeric precision issues when the
checks were based on exact string matches, and then the string
rounding changed one day.

It is not impossible to write a good check, but as an
understatement, it is rather complicated.


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