[GRASS-user] CHELSA climate data set

[Markus Metz]

On Tue, Feb 7, 2017 at 3:43 PM, Markus Neteler <neteler at osgeo.org> wrote:
>
> On Tue, Feb 7, 2017 at 3:32 PM, Markus Metz
> <markus.metz.giswork at gmail.com> wrote:
> [...]
> > Unfortunately it changes East from 179.9998611 to 179.9998597 and north
> > from 83.9998611 to 83.9998604.
> >
> > The more serious problem is that GRASS can not handle ll coordinates
like
> > 180:0:0.50W or 90:0:0.5S.
> >
> > I have relaxed the ll restrictions in my local copy and can now import
> > CHELSA and other for GRASS problematic ll datasets without getting e.g.
a
> > narrow N-S strip, or GRASS fixing a subtle rounding error that in fact
is
> > not an error. That means after each import I have to manually check if
> > resolution and extents make sense, and if in doubt fix them with
r.region.
>
> That's probably rather more a power user task than common user
> knowledge...

Why a power user task? r.region is an easy to use module, as long as you
know the correct grid geometry. And with my relaxed ll restrictions I get
less errors and more usable results, in fact I need to use r.region less
often than before.

> Is there anything we could do at libgis level like
> relaxing the ll restrictions along with appropriate user messages?

Yes. The first points would be ll_scan.c, ll_format.c and adj_cellhd.c.
That should also remove cryptic errors like "ERROR: Syntax error in cell
header".

> More and more global datasets are getting published, so the issue will
> likely come up more frequently. Just to make it a bit easier :-)

For a start, it would be nice if you can create a full SRTM mosaik (not so
new data) in GRASS.

Markus M

>
> markusN
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