[GRASS-user] Determine surface areas

[Moritz Lennert]

On 05/03/09 23:15, ich at the-masterplan.net wrote:
> Hi!
> 
> I am still working on the extended problem and so far i have done the
> following.
> I created circles and sectors in autocad and imported the dxf file (first
> one sector at a time).
> The import didn't seem to work that well, so i converted lines to
> boundaries and used v.clean to get areas, and inserted a centroid with
> v.digit and created a rastermap with v.to.rast (source: val, and
> featuretype area).
> using the rastermap as mask I can use r.report or r.stats to get the
> waterarea/watercells.
> 
> Because there are 160 of these areas i was wondering if there is a
> possibility to use all of the areas at once (or at least more than one at
> a time) assign some kind of an ID to every area and get the results
> separately for every area.
> trying to use more than one area at a time always got me the total stats
> for all areas.

Just give each centroid a different category value (e.g. using 
v.category, or by hand using v.digit), then v.to.rast use=cat. Then 
r.stats/r.report should give you the result by category.

Moritz