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Convert the vector map to raster with the command:
v.to.rast input=edifici output=edifici.mask use=val layer=1 value=1 rows=4096
Remember that this conversion is run following the region settings. You can view the region settings with:
Now the resulting raster map becomes our
r.mask input=edifici.mask maskcats=*
From now on, all subsequent operations will be limited to the cells defined in our
MASK, corresponding to built
areas or settlements.
The simplest analysis we can run is
d.histogram. These are the histograms of elevation and aspect for the whole of our study area. Aspect is calculated counterclockwise from east, thus 0 = 360 = E, 90 = N, 180 = W, 270 = S. See http://grass.itc.it/grass62/manuals/html62_user/r.slope.aspect.html for the manual page of
MASK results in these histograms:
This simple exploratory analysis leads us to understand that in the study area there's a strong preference for sites exposed S-SE, built mostly around 700 meters above sea level.