[GRASSLIST:6126] Re: dissolve common boundary

[ivan marchesini]

Dear all...
I try to answer all your questions and remarks...

-The areas are obtained from overlay operations and are perfectly
overlapping (also zooming in....)

- I have tried to search the "column" option in v.category, but I didn't
find it

- I didn't understand how the new parameter works... if I put new=1 the
table is not created... and if I put new=1 the original category are
mantained (boundary not dissolved)... which value is better???

how can I solve the problem???  

thank you very much...

ivan


 




Il giorno ven, 11-03-2005 alle 10:28 +0100, Moritz Lennert ha scritto:
> On Thu, March 10, 2005 19:56, ivan marchesini said:
> > Dear Hamish, dear Markus...
> > I have still problem to dissolve boundaries...
> > I will try to explain better the problem...
> > I have a lot of areas (a reclassified landuse map) in a vector map...
> > some of these poligon have the same values in a column of the
> > database...
> > for example: two touching areas have the same code=31
> > I would like that these two ares will became one single area .... and
> > the same for the other touching areas which have equal code values....
> >
> > I have tried
> > v.extract -d input=landuse output=landuse_diss type=area new=-1
> >
> >
> > but the output is exactly the same map as the input
> >
> > where I'm wrong???
> > can you help me??
> 
> It dissolves, if the category values are equal, not any value in the attribute
> table. So, you will first have to use v.reclass with the 'column' option to
> take new category values from the desired column and then v.extract -d on the
> resulting map.
> 
> Moritz
> 
-- 
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
fax: +39(0)755853756