I'm running v.clean on a merge of 2 vector layers of pipeline data. I initially found the issue trying to clean undershot laterals not properly attached to main lines, scale is undershot by about 1 foot.

These are my v.clean settings:

enter image description here

This is an example of the undershoot that gets cleaned with the above settings:

enter image description here

However, when I use v.clean (Thresh.=0.00001, v.in.ogr min snap tol.=1, v.in.ogr.min area=0.0001) I proceed to break existing lateral/main geometries of about 2.4 ft.

Example of the lateral that disappears, slight dangle after intersection:

enter image description here

The post v.clean, now missing lateral, did have an overshot/dangle. Could that cause the snap to remove the geometry?

Any help appreicated!

  • I always run a check geometry any time the tool doesn't work as expected. I see you set the v.in.ogr snap to 1 but you might set your snap tool theshold to 1 as well. The break tool is selected by default so if you don't turn it off it needs a threshold as well even if just 0.
    – John
    Commented Mar 13 at 10:58
  • I think this ended being related to the similarities in the lengths of the 2 objects observed
    – Derek_P
    Commented Mar 13 at 20:19

1 Answer 1


So, this appears to be specifically related to the input level I was providing for v.clean's threshold value for the snap cleaning tool, which I was using. My initial value of 0.00001 was sufficient to create the snap I required, but adversely deleted an existing topology. As I've understood it, the behavior I was seeing was related to the similarity in the effected topologies. (0.000009 deg for the adversely effected and 0.000004 deg for the needed snap).

Setting the Threshold to 0.000006 has satisfied my requirement for the snap while maintaining the fidelity of the existing topologies.

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