[GRASS-user] Determine surface areas

[Markus Metz]

Moritz Lennert wrote:
> 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.
Or v.to.db option=area?

Markus M