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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.

Does anybody know a Plugin? Would be great!

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You can use the GRASS Toolbox for that.

Cleaning of topology of a SHAPE file using the GRASS Toolbox

  1. Load the SHAPE file into QGIS
  2. Use existing GRASS mapset (or create a new one) with matching projection settings
  3. 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 ( Some topological problems may be reported depending on the quality of your SHAPE file.
  4. 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.
  5. Export the cleaned map to SHAPE format: File management -> Export from GRASS -> Export vector from GRASS -> v.out.ogr
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The new Topology Checker Plugin will be available in the next release. You can see it at work in this video:

More info:

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Does the new Topology Checker can clean topology errors or manage topology with rules similarly to ArcGIS 10? Is there a segment snapper tool like in ArcGIS 10? Thank you. – Below the Radar Jul 9 '13 at 17:09
Has this plugin already been released? If yes, where can I find it? – Stefan Jul 22 '13 at 9:26

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