[GRASS-user] create a mask to exclude plate area

[Etienne DELAY (deust 2010)]

> How? Which command(s) exactly? Using r.mapcalc? There is also r.mask [1]
> Also, tres-important, did you define the "region" of your interest using 
> "g.region"[2]?
> 
>> Now I have to exclude the plate areas (eg trays Spanish) but I can not
>> see any use for this test.
>> I thought r.mapcalc place an order with a request to both  area and on
>> slope.
> 
> That is right. r.mapcalc (or most of the raster modules) will ignore the 
> MASKed-out cells by the raster map named MASK.
> 
> Radom example grepped from the grass-user list:
> 
> --%<--- Re: How To use a raster MASK correctly? --17/10/2009 20:09 --%<---
> Figured it out.  Used the following r.mapcalc expression:
> r.mapcalc "new_hillshade=if(europe_dem < 100, 180, europe_hillshade)"
> -->%---
> 
> Cordialement, Nikos
> 
> ---
> [1] <http://grass.osgeo.org/grass65/manuals/html65_user/r.mask.html>
> [2] <http://grass.osgeo.org/grass65/manuals/html65_user/g.region.html>
> 

Hello Nikos
sorry for the French, I need to think in my language :-)
So I have no problem using r.mapcalc for 1st and 2nd criteria, and to
assemble the two masks. The region is also parameterize, but now, it has
become a 3rd test, I must arrive in isolating the flat portions of the
mountain in Spain, if not that is reflected in part authorize my mask,
but not know  structural problems in they vineyards ...

I want to use something like:

r.mapcalc "Maskplate= if((Area>100000ha && slope<=10%), 1, null())

mais l'utilisation de aire ne me satisfait pas vraiment.... parce quelle
peut changer en longueur et largeur...

but the use of area does not really satisfy me .... because what can
change in length and width ...

Is there a solution would be to make visual grade, to define the
geomorphological unite?

thank you very much ;-)

-- 
Cordialement

Etienne DELAY
Deust "Webmaster et gest. d'intranet" (IDSkype : etienne.delay.tic)
Master IUP "valorisation du patrimoine et aménagement du territoire"