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

[FAROUX STEPHANIE]

Markus Neteler wrote:
> 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
>
>   
Cool it works thank you