[GRASS-user] Remove islands with v.extract problem (again)

[Blumentrath, Stefan]

Hi,



I am trying to remove islands (here also in the topological sense) from a set of lake polygons.



The polygon layer contains only the water bodies (means islands within the lakes have no category).



I tryed v.extract -d as well as v.extract list/cats=1-99999999 both in GRASS 6 and 7 (on Ubuntu 12.04 LTS).



In all tests the layer did not get modified as expected and islands were still present.



This topic has been (repeatedly) discussed earlier. But the proposed solution (also in the manual of v.extract) did not work for others as well (quite some time ago):

http://lists.osgeo.org/pipermail/grass-user/2006-January/032016.html



I am wondering what the problem might be?

Any idea? I can provide sample data if that might help...



I am now using ST_ExteriorRing from PostGIS (http://postgis.net/docs/manual-2.1/ST_ExteriorRing.html) to achieve what I want, but it would be nice to have a GRASS solution...



Cheers

Stefan


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