Hello,
thanks for your help. but this is not all that I was looking for.
>> Basically, I'd like to run v.extract/v.overlay not on a
>> vector-to-vector basis but on a vector-to-raster basis.
>
> g.region rast=dem_name
> v.in.region dem_box
>
> then v.overlay or v.select, depending on if you want to want to clip
> touching vector areas at the bound or not.
=> With your tip I am just creating a boundary vector with the region
extends.
But my raster has been created by mapcalc:
1. I created the raster like this:
(elev => SRTM DEM)
r.mapcalc "myraster=if(elev < 1000,elev, null())
=> now I have a huge (by area) raster which contains cell values in
floating points.
=> The raster now has areas with NULL values because the terrain
elevation is above 1000 m.
2. now I have the vector
landcover: Global Land Cover 2000
Now I would like the polygons from the landcover, which are situated
below 1000m.
How can I achieve this?
My idea:
a) simplify the raster because the raster is too complex for data type
conversion:
r.mapcalc "myraster_simple=if(myraster,1, null())
b) convert to vector:
r.to.vect -s in=myraster_simple out=myraster_simple
c) run v.overlay.
Is there a simplier and more efficient approach?
How do I also extract those areas of the raster which intersect with
certain landuse types?
Thanks and kind regards,
Timmie
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