[GRASS-user] Re: r.in.gdal oddity

Hamish hamish_b at yahoo.com
Thu Nov 3 00:17:37 EDT 2011

Hi, coming to this thread a bit late, sorry if I miss the point;
I'll study the rest of the thread/situation better asap, but some
general comments--

Markus wrote:
> > Just force it to be 180W and 180E... I thought (the -l
> > flag) it is just a recent addition to GRASS 6.4, so maybe
> > it needs a some t.l.c...

AFAIK it is working as intended and without bugs.

The -l flag is intended to get the raster data into the lat/lon
location, at the expense of breaking (to a greater or lesser
extent) the bounds. When you use that flag, you pretty much Must
run r.region (and/or g.region + r.mapcalc in a crop operation)
before doing anything else. Converting from grid-confluence to
cell-center convention could also require working in a 1/2 cell

see the "Error Messages" section of the r.in.gdal help page
for expanded explanation and help with the -l flag.

As MarkusM noted, 0-360 is valid and used by planetary scientists,
and I notice some modern GRIB raster data from the US National
Weather Service/US Navy ocean models use that now too.

The -l flag's longitude fix is really just a while-we're-here
thing, the main adjustment the flag is intended to deal with is
the hard +/-90 deg latitude limit.

>         G_warning(_("Map bounds have been constrained to geographic "
>             "coordinates. You will almost certainly want to check "
>             "map bounds and resolution with r.info and reset them "
>             "with r.region before going any further."));
>     }
> ... the warning is not particularly clear to me - "reset
> them" in this sense?

"You will almost certainly want to check map bounds and
 resolution with r.info and reset them with r.region before
 going any further."

maybe I'm not understanding the question or missing an implied
noun, but "them" == map bounds and resolution in this context.


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