[..] Markus M:
> >> I assume the global mangroves map should not have overlapping > >> polygons, therefore as long as there are overlapping areas and/or the > >> number of centroids is not equal to the number of input polygons, more > >> cleaning is needed. Nikos A: > > Unfortunately it seems there are overlapping polygons. Markus M: > Obviously so, and fairly large overlapping areas according to your > output even for snap=1e-6: > Overlapping area: 5.32085E+09 (41538 areas) > > Therefore there are probably logical errors in the input data, for > example the same mangrove polygon might be present more than once. > This can not be cleaned automatically with v.in.ogr or v.clean. You > can investigate overlapping areas in the imported vector with d.vect > type=area layer=2 (only overlapping areas have a category in layer 2). It looks _not_ good at all. Layer 2 over layer 1 uploaded at: <http://picpaste.com/global_mangroves_usgs_2011_imported_snap_1e-6_layer2_over_layer1-EWItDQK6.png>. I have also found the relevant "factsheet" for the Global Mangrove Distribution (USGS, 2011), which does not help very much I think: <http://www.unep-wcmc.org/medialibrary/2013/01/08/51d9d8c6/mangroves_usgs.pdf> Nikos _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
