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<p>Hi,</p>
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<p>I am trying to remove islands (here also in the topological sense) from a set of lake polygons.</p>
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<p>The polygon layer contains only the water bodies (means islands within the lakes have no category).</p>
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<p>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).</p>
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<p>In all tests the layer did not get modified as expected and islands were still present.</p>
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<p>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):</p>
<p><a href="http://lists.osgeo.org/pipermail/grass-user/2006-January/032016.html">http://lists.osgeo.org/pipermail/grass-user/2006-January/032016.html</a></p>
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<p>I am wondering what the problem might be?</p>
<p>Any idea? I can provide sample data if that might help...</p>
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<p>I am now using ST_ExteriorRing from PostGIS (<a href="http://postgis.net/docs/manual-2.1/ST_ExteriorRing.html">http://postgis.net/docs/manual-2.1/ST_ExteriorRing.html</a>) to achieve what I want, but it would be nice to have a GRASS solution... </p>
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<p>Cheers</p>
<p>Stefan</p>
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