Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I read about the planarize function in ArcGIS, which seem to do exactly what I want. Is there a similar feature in QGIS or another free tool?

I have a shapefile with various shapes intersecting each other and I want each intersection to become a node and between every two nodes to have a simple line.

The goal is to easily convert my .shp in .osm and use it with Graphserver. As it is, Graphserver says I don't have edges, and I deduced the above is my problem.

Thanks a lot

share|improve this question

In GRASS GIS which is topological you can use for this operation. You can access it through the QGIS-GRASS Toolbox.

share|improve this answer
Hi! I had a look about the documentation, I'm not sure about the end result I should get to be able to import this in the graphserver… – charlax Oct 6 '11 at 1:44
You can then export to a OGR supported format with v.out.ogr. – markusN Oct 8 '11 at 23:59
Odd the documentation isn't very explicit that it handles intersections. Did you try this and does it work? – Sideshow Bob Sep 17 '12 at 13:10
Not sure this works - see my other answer – Sideshow Bob Dec 10 '15 at 13:28

In GRASS GIS the v.clean tool can be set to break intersections. The rmsa and rmdupl options to v.clean are useful as well.

Returning to this question for a third time: the snap option to v.clean will snap together features by altering their shape to fix apparent intersections, etc. snap followed by break should thus do a job similar to ArcGIS Planarize.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.