[GRASS-user] v.in.ogr imports some areas of shapefile twice or more

GRASS GRASS user
,
1

Hello,
I have a shapefile containing 150 polygons.

After importing this shapefile with v.in.ogr and then adding it to a qgis prject
I observe that it has more polygons than the original data source.
I tested it by overlaying the original shapefile in QGIS as a normal (non-GRASS)
vector.

This is really strange. What could be the cause for this?

Regards,
Timmie

2

On 31/07/08 10:03, Tim Michelsen wrote:

Hello,
I have a shapefile containing 150 polygons.

After importing this shapefile with v.in.ogr and then adding it to a qgis prject
I observe that it has more polygons than the original data source.
I tested it by overlaying the original shapefile in QGIS as a normal (non-GRASS)
vector.

This is really strange. What could be the cause for this?

It could be the result of the cleaning process done by v.in.ogr. If overlaps or slivers are large enough GRASS will make polygons out of them. You can control the size threshold with the 'min_area' parameter.

Moritz

3

Tim Michelsen pisze:

I have a shapefile containing 150 polygons.

After importing this shapefile with v.in.ogr and then adding it to a
qgis prject I observe that it has more polygons than the original data source. I tested it by overlaying the original shapefile in QGIS
as a normal (non-GRASS) vector.

This is really strange. What could be the cause for this?

Post 'ogrinfo -al -so' of the shapefile and of the GRASS vector (point
ogrinfo at the 'head' file of the GRASS vector map, sth. like
/home/grassdata/<location>/<mapset>/vector/<vector map>/head).

Maciek

--
Maciej Sieczka
www.sieczka.org