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

[Markus Metz]

Hi Peter,

On Tue, May 1, 2018 at 11:33 PM, Peter Tittmann <ptittmann at gmail.com> wrote:
>
> 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..

the reason why this works is that these incorrect boundaries are not
exported. When re-importing, you will get a clean vector but some of the
original areas are gone. If you still want to find out what went wrong
where, you would need to find out where these incorrect boundaries first
appeared in the processing steps of your original vector.

Markus M

>
> 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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