[Qgis-user] Check geometry validity tools

[Jukka Rahkonen]

Salvatore Larosa <lrssvtml at ...> writes:


> 
> please, if it is not a sensitive data would be useful if you could
> share a sample of the dataset.
> my guessing here is that you should run the make valid script (lwgeom
> algotithm by processing plugin) before.

Hi,

Such data are easy to acquire because OpenStreetMap has loads of three-point
(A-B-A) polygons. I have been trying to create such artificially sometimes
because they make trouble with most other software despite Mapnik but I
haven't been successful yet. It is impossible to digitize a three point
polygon with QGIS or OpenJUMP, and SQL that should yield A-B-A polygon leads
to "NULL" in Spatialite and to an error with PostGIS.

select geomfromtext('POLYGON ((0 0,1 1,0 0))');

-Jukka Rahkonen-