[GRASSLIST:9822] Re: v.extract area with holes but without islands

[ivan marchesini]

Dear Roger..
it could be I'm wrong but I think that island are automatically present
when you have a hole inside an area poligon...
grass dedects the island when it build topology.. it means that there is
an hole inside the poligon but you can simply verify that there is not a
centroid inside the island.... and this is correct because the island is
not an area (it has not attributes....)
instead the poligon has a centroid...

if you try to do the spatial sampling you will see that only points
falling in the area will be sampled, instead those falling in the island
(the hole) will be discared...

I hope this help...

ivan





Il giorno ven, 13/01/2006 alle 12.06 +0100, Roger Bivand ha scritto:
> move the islands from the vector representation? The 
> output is to be used for spatial sampling, so sample points falling in
> the 
> holes should be discarded. I think v.build is assuming that holes
> should 
> be filled with islands in each case.
-- 
Ivan Marchesini
Department of Civil and Environmental Engineering
University of Perugia
Via G. Duranti 93/a 
06125
Perugia (Italy)
e-mail: marchesini at unipg.it
        ivan.marchesini at gmail.com
tel: +39(0)755853760
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