Thanks Markus for the hint. Replies below. Il 10/02/2018 22:53, Markus Metz ha scritto: > This seems to be a reprojection problem. > > If you reprojected the vector data in GRASS with v.in.ogr + v.proj, this > is a problem of GRASS, granted that v.in.ogr did not complain about > vector topology. > > If you reprojected non-topological polygons, this is a common problem > when reprojecting non-topological polygons. Please import these polygons > first into GRASS, then reproject within GRASS and run v.generalize on > the reprojected GRASS vector.
I'm not explicitly reprojecting it. I tried the command from within QGIS>Processing. Here the relevant commands: g.proj -c proj4="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs" v.in.ogr min_area=0.0001 snap=-1 input="/tmp/processing63c3c94ab569415fba39f41c12e3e48f" layer=1518196447.565 output=tmp1518196448046 --overwrite -o g.region n=5538851.39594 s=5150937.66442 e=1377191.37538 w=1004373.60434 res=100 v.generalize input="tmp1518196448046" method=douglas threshold="1000" look_ahead="7" reduction="50" -l output="output081005b4fafd473bbfa438a964de80f1" --overwrite All the best. -- Paolo Cavallini - www.faunalia.eu QGIS & PostGIS courses: http://www.faunalia.eu/training.html https://www.google.com/trends/explore?date=all&geo=IT&q=qgis,arcgis _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user