[GRASS-user] v.clean Failed to build area

[Peter Tittmann]

Hi Markus,

I'm ashamed to admit that I hacked my way into fixing this problem by
exporting the vector dataset using `v.out.ogr` to a geopackage then
importing it. The cleaning tools in v.in.ogr seemed to solve my problem..

Very clumsy, but it worked.

Thank you!

Peter

On Fri, Apr 27, 2018 at 11:51 AM, Markus Metz <markus.metz.giswork at gmail.com
> wrote:

> [ please keep this on the GRASS mailing list ]
>
> On Fri, Apr 27, 2018 at 6:43 PM, Peter Tittmann <ptittmann at gmail.com>
> wrote:
> >
> > Hi Markus,
> >
> > grass72 -v
> > GRASS GIS 7.2.2
>
> This is already the latest 7.2 release. You might try GRASS 7.4.
>
> >
> > i will try to figure out how to get the latest release up and running.
> If you have any suggestions for fixing the boundaries, that would be great.
>
> If upgrading to the latest GRASS 7.4 release does not help, I would need
> the data for testing to find out why removing small areas fails. If the
> vector has been imported from an external datasource without modification
> of the geometries inside GRASS, this version would be preferable. Otherwise
> the history of plot_pa_with_lidar at project_area would be helpful (v.info
> -h).
>
> Markus M
> >
> > Peter
> >
> > On Thu, Apr 26, 2018 at 11:19 PM, Markus Metz <
> markus.metz.giswork at gmail.com> wrote:
> >>
> >>
> >>
> >> On Fri, Apr 27, 2018 at 1:37 AM, Peter Tittmann <ptittmann at gmail.com>
> wrote:
> >> >
> >> > Hi,
> >> >
> >> > I am attempting to use the `rmarea` tool in v.clean with a threshold
> of ~ 1000 sq meters.
> >> >
> >> [...]
> >>
> >> >
> >> >  I am getting a rather cryptic message ‘Failed to build area’.
> >> >
> >> > > v.clean -c --overwrite --verbose input=plot_pa_with_lidar at project_area
> output=plot_pa_rmarea tool=rmarea threshold=1017.2
> >> > --------------------------------------------------
> >> > Tool: Threshold
> >> > Remove small areas: 1017.2
> >> > --------------------------------------------------
> >> > WARNING: Vector map <plot_pa_rmarea> already exists and will be
> overwritten
> >> > Using native format
> >> > Copying features...
> >> >  100%
> >> > Rebuilding parts of topology...
> >> > Building topology for vector map <plot_pa_rmarea at project_area>...
> >> > Registering primitives...
> >> > 1720636 primitives registered
> >> > 3439992 vertices registered
> >> > Building areas...
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> > WARNING: Area of size = 0.0 ignored
> >> >  100%
> >> > 499671 areas built
> >> > 6004 isles built
> >> > Attaching islands...
> >> >  100%
> >> > Attaching centroids...
> >> >  100%
> >> > Topology was built
> >> > Number of nodes: 728615
> >> > Number of primitives: 1720636
> >> > Number of points: 0
> >> > Number of lines: 0
> >> > Number of boundaries: 1222309
> >> > Number of centroids: 498327
> >> > Number of areas: 499671
> >> > Number of isles: 6004
> >> > WARNING: Number of incorrect boundaries: 9
> >> > WARNING: Number of duplicate centroids: 14
> >> > --------------------------------------------------
> >> > Tool: Remove small areas
> >> > ERROR: Failed to build new area
> >>
> >> I guess the problem are these 9 incorrect boundaries. Which GRASS
> version are you using? Can you try again with the latest release in case
> you are not using the latest release?
> >>
> >> Markus M
> >
> >
>
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