[GRASS-user] Raster Map subset

[Micha Silver]

Rich Shepard wrote:

> On Fri, 5 Feb 2010, stephen sefick wrote:
>
>> Is there a way to get a subset of a larger raster map.  I have zoomed
>> into an area and would like to make a raster map only containing that
>> area. Can I do this? I am going to use this as input into R for some
>> topmodel runs.
>
> Stephen,
>
>   Yes, you can. This subject has come up several times in the past 
> month or
> so so the archives have a lot of options for you. One to look at 
> closely is
> v.in.region. After zooming to the area you want, run v.in.region and save
> that vector map. You can then use it with the g.region command to 
> limit the
> displayed bounds of your raster map. You can use r.patch to make a new
> raster map that's the size of the newly created vector map.
I'm not sure this is entirely correct. v.in.region saves the current 
*computational* region to a vector, not the area zoomed to. Setting the 
desired region first with g.region, I think, is the correct way to go. 
Then r.mapcalc can create a new raster, limited to the new smaller region.
>
>   Are you aware of r.topmodel within GRASS?
>
> Rich
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-- 
Micha Silver
Arava Development Co. +972-52-3665918
http://surfaces.co.il