[GRASS-dev] vector layer contains error not detected by v.build nor cleaned in v.clean

[Markus Metz]

On Wed, Jan 25, 2017 at 12:31 PM, Paulo van Breugel <p.vanbreugel at gmail.com>
wrote:
>
> Dear all,
>
> I have a vector layer which I cleaned up using v.clean. It all appears to
be fine, but when trying to export using the libkml in v.out.ogr and the
type=area option, I am getting the warning and error messages like below:
>
> Warning 1: Ring Self-intersection at or near point
> 88.100626640406631 27.668444701473838
> ERROR 6: Invalid polygon
> Warning 1: Ring Self-intersection at or near point
>
> In the resulting kml file, some of the polygons are missing. If I use the
kml output in v.out.ogr, I am not getting any warnings, but similarly, some
of the polygons are missing.
>
> When I import the layer in Spatialite and check the geometries I am
getting similar warnings / error messages, e.g.,:
>
> 27 Ring Self-intersection at or near point 82.397900772562522
29.707213605319616
>
>
> How can I identify and clean these issues in GRASS? Checking for
topological errors with v.build does not result in any error, and I tried
the various tools in v.clean to no avail.

Did you try
v.clean -c type=boundary tool=rmsa,break,rmdangle threshold=0,0,-1
?

Also try v.build -e

Markus M

>
> Paulo
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