Markus Metz-3 wrote > On to the next one: > > On Fri, Oct 20, 2017 at 10:07 PM, Helmut Kudrnovsky <
> hellik@ > > wrote: >> > [...] >> >> o World database of protected areas (~ 1 GB): >> >> https://www.protectedplanet.net/ > > First problems: lots of warnings like > WARNING: Degenerate island (1 vertices) > WARNING: Feature (cat > <XY> > ): degenerated polygon (1 vertices) > > These are invalid geometries in the input >> >> >The real cleaning happens only if the snap option is set to > 0. > > From the WDPA manual: > "There are many overlapping protected areas in the WDPA. These can be > overlapping areas with > different IUCN categories or the overlap of national protected areas with > designations under > regional or international conventions and agreements." > > Thus I would not regard all overlapping areas as errors. I used a spatial > subset for testing: > v.in.ogr spatial=5.467,43.842,14.3,50.558 > that's the Alps and a bit around. > > v.in.ogr suggests a snapping value in the range 1e-5, 1e-13. I started > with > 1e-9 and got rid of the warnings like > WARNING: Unable to calculate area centroid > > but some incorrect boundaries remained in the output. With snap=1e-8, > these > incorrect boundaries disappeared. > > The output contains lots of small areas. According to GIS_AREA in the > attribute table, the smallest areas in the input are larger than 100 > square > meters, so I cleaned with v.clean tool=rmarea thresh=100, getting rid of > 60% of all areas in the output. > > In earlier years, the WDPA was separated into different shapefiles: one > for > marine areas, one for IUCN I-VI, one for all other areas. Now everything > is > in one shapefile / GDB. When importing these data, a spatial and an > attribute filter should be set for v.in.ogr. thanks for also testing this data set. I'll add some notes in the wiki about importing these datasets. thanks. ----- best regards Helmut -- Sent from: http://osgeo-org.1560.x6.nabble.com/Grass-Users-f3884509.html _______________________________________________ grass-user mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-user
