[GRASS-user] large shapefile not importing properly with v.import

[Helmut Kudrnovsky]

>Can you provide examples where v.in.ogr with cleaning/polygon conversion did
not work, but v.in.ogr -c + >v.clean produced better results?

really good data sets with all kind of (topological) mess are (from [correct
and incorrect] overlapping to self intersections etc):

o Natura 2000 data (~ 1GB):

https://www.eea.europa.eu/data-and-maps/data/natura-8#tab-gis-data

o World database of protected areas (~ 1 GB):

https://www.protectedplanet.net/

>The real cleaning happens only if the snap option is set to > 0.

v.in.ogr gives some hints about the snap option, sometimes I don't know what
should be the optimal setting.

>noticed that v.in.ogr complains about overlapping areas, which were input
polygons that should not >overlap, but snapping did not help there, instead
I needed to remove small areas afterwards with v.clean.

same experiences here.

>Should the current min_area option of v.in.ogr also be used to remove small
areas in the output?

never used this option:

min_area=float
    Minimum size of area to be imported (square meters)
    Smaller areas and islands are ignored. Should be greater than snap^2
    Default: 0.0001

do you mean the small areas shouldn't be imported or small areas should be
added to the neighbor area with the longest adjacent boundaries?



-----
best regards
Helmut
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