I have two Shapefiles with Polygons ( City and Forerst)
Is there a Plugin who is able check the topology (QGIS)?
Like "Knots do not overlap" or something like that. I dont want that they overlap.
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You can use the GRASS Toolbox for that.
Cleaning of topology of a SHAPE file using the GRASS Toolbox
- Load the SHAPE file into QGIS
- Use existing GRASS mapset (or create a new one) with matching projection settings
- Now you have to transfer the SHAPE file from QGIS to GRASS using Toolbox -> File management -> Import into GRASS -> Import vector into GRASS -> Import vector into GRASS from QGIS view (v.in.ogr.qgis). Some topological problems may be reported depending on the quality of your SHAPE file.
- These topological problems we can fix now in GRASS via toolbox using the topology tools: Vector -> Develop map -> Toolset for cleaning topology of vector map -> v.clean.break. Define a threshold in map units (for example 0.5 [m] or likewise). Analyse the printed report, probably the threshold needs to be adjusted or a different topology cleanup tool to be used. Click then on view output to show the result as map.
- Export the cleaned map to SHAPE format: File management -> Export from GRASS -> Export vector from GRASS -> v.out.ogr