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I'm currently doing a project on finding blocked roads in a road network layer. I've figured that I can use the topology checker with the rule 'must not have dangles' and find them this way. But I can't figure a way to export this to a layer or any other file format I can use for further analysis. Any ideas?

Please see the attached image of my result then it might be more clear what I mean (the QGIS version is in Danish, please let me know if it's a problem)

The topology-checker I'm refering to is the one in Vector -> Topology-checker where you have the option to define rules.

I should add that my road network is combined to 1-line feature and not the seperate road sections. In this way I'm able to find the errors with the 'must not have dangles' rule.

I am aware of ArcGIS has this export topology option, but since I'm mainly using QGIS and Mapinfo I prefer to find a solution through these.

QGIS 2.6 - Topology errors

  • This is the same issue that exists in ARC. The errors that get created for dangles have no geography associated with them and are just a layer file which isn't editable. The same I feel is true with the Topology Editor in QGIS which does something similar. And I have yet to find anything that will create the errors as say a shapefile that you can manually delete when you have fixed them in QGIS unfortunately... – pjordan526 Dec 10 '15 at 21:45
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Perhaps another tool you can try using is the Check Geometry validity (Vector > Geometry Tools > Check Geometry Validity).

I think this tool also checks for dangles but I'm not sure, you cannot select which type of errors you want to search for. But it does allow you to save the locations of those errors as a point shapefile:

Check geometry validity

Hope this helps!

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    Thanks for your reply! I also tried this tool before and unfortunately it doesn't do the job in the same way as the other topology checker. Maybe it's because you can't define the rules. Not sure.. – Anders MJ Mar 6 '15 at 11:48
  • Yes I think you're right. Hopefully others can advise if this is indeed possible with the Topology Checker =) – Joseph Mar 6 '15 at 11:57
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    Just been looking at the source code of Topology Checker and there's no way to save the errors as anything. Its in C++ so tweaking it isn't as easy for me as it would be if it was in Python. Suggest you make a feature request to the author. – Spacedman Dec 10 '15 at 23:03

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