[GRASS-user] to define a region which is not rectangular

Markus Neteler neteler at osgeo.org
Thu Feb 19 04:46:27 EST 2009


On Thu, Feb 19, 2009 at 9:33 AM, FAROUX STEPHANIE
<stephanie.faroux at meteo.fr> wrote:
> Hi,
> In my raster map sea pixels and missing data have the same null value. I'd
> like to separate the two but i don't have a sea/land mask. Missing data are
> concentrated in some areas.
> How can i do it?

You can use r.clump to enumerate the individual raster
areas. Then use r.mapcalc with an if condition to select
the areas of interest and save them into a new map.
This map can then be used as MASK or whatever.
Or use the if condition to change to a new value directly
and save the result into a new map.

Markus


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