I'm trying to convert a lines layer from Ordnance Survey which is made up of field boundaries, river banks, woodland boundaries and houses etc into a polygon layer, but only 'polygonise' the fields.

Below is the direction I've taken so far:

Ordnance Survey Data with Estate boundary in red: enter image description here

I used an expression to select and save only the field boundaries, clipped it against the estate boundary and dissolved the resultant layer:

Highlighted fields have simple geometries and those not highlighted would need manual editing following the processing enter image description here

Result when I do lines to polygons (same result prior to dissolve): enter image description here

I tried intersecting the estate boundary and lines but this resulted in no features. I later found the SAGA processing tool 'Polyon-line intersection' which has given me the best result so far but still not great:

enter image description here

How can I do this?

  • Have you tried the "polygonize" algorithm? – ndawson Aug 17 '18 at 21:22
  • That seems to provide the best result, thank you. Only issue is that the lines do not always join up, or overlap and the odd duplicate lies about. This makes the geometry invalid. Long story short, trying to achieve this may just cause a bigger headache than doing it manually! – James B Aug 20 '18 at 15:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.