[GRASS5] [bug #2397] (grass) v.clean dissolve problem for areas

[Radim Blazek]

On Tuesday 04 May 2004 20:42, Otto Dassau wrote:
> this is the original soils map from spearfish57
>
> Number of nodes     :   2181
> Number of primitives:   2883
> Number of points    :   0
> Number of lines     :   0
> Number of boundaries:   2146
> Number of centroids :   737
> Number of areas     :   737
> Number of isles     :   42
> Number of incorrect boundaries   :   7
>
> Then I extracted all areas with cat>20:
> v.extract in=soils out=soils2 type=area,centroid where='cat>20'
>
> Number of nodes     :   1960
> Number of primitives:   2484
> Number of points    :   0
> Number of lines     :   0
> Number of boundaries:   1908
> Number of centroids :   576
> Number of areas     :   595
> Number of isles     :   71
> Number of areas without centroid :   19
>
> in the resulting map centroids are missing, because some areas seem to be
> not correctly extracted. 

Are you sure that areas without centroids are not surrounded by 
areas with cat>20? Any polygon closed by boundaries is area.
Category is used to identify areas you want.

> And you said 'some time ago' that this is not a
> v.extract problem and would have to be solved by adding a dissolve function to
> v.clean, as described with the upper figures.

I hope I did not. 'dissolve' may be v.extract option, but does not make 
sense for v.clean.

Radim