[GRASS-user] areas without centroids

ivan marchesini marchesini at unipg.it
Wed Oct 4 05:05:29 EDT 2006

Dear grass users,
I have this problem:
I have a large vector map (containing around 30000 areas)
this is the result of v.build:

Topology was built.
Number of nodes     :   281822
Number of primitives:   302330
Number of points    :   0
Number of lines     :   0
Number of boundaries:   272346
Number of centroids :   29984
Number of areas     :   30062
Number of isles     :   9554
Number of areas without centroid :   78

the map is the land use map of a region.. so it should not contain areas
without categories...
the map is connected to a table containing only 28 records describing
the type of land use (more centroids are connected to a single record)

I'm quite sure that there are not "holes" in the map, but I can't
explain the presence of 78 areas without centroids..

I have exported the map with the option of export only the areas having
category and v.in.ogr said that he have skiped 78 feature  and that he
have exported 29984 areas (it seems correct).

then, when I try to reimport the map, v.in.ogr say he have created a map
containing a larger number of areas.. not 29984 as I was expecting..

I can't figure which is the problem.. 
how can I understand where are these areas without centroid??
how can I remove them (if they are not "holes" between other areas with

many thanks for your suggestions!!!


Ivan Marchesini
Department of Civil and Environmental Engineering
University of Perugia
Via G. Duranti 93/a 
Perugia (Italy)
e-mail: marchesini at unipg.it
        ivan.marchesini at gmail.com
tel: +39(0)755853760
fax: +39(0)755853756
jabber: geoivan73 at jabber.org

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