I am working on QGIS latest version 2.12.3.

I am digitizing a polygon. It represents a riparian buffer of a river. The polygon made a continuous « loop » with a widht of 50 meters. I want to split my polygon into 8 sections that can be dealt with seperatly.

Polygon i am trying to split

My problem is that i am unable to split to polygon. When i am using the « splitting » tool in advenced digitizing menu, the polygon does not split. It says « Invalid Geometry ». Therefore, the poylgon doesn't split. It suprise me because the same request use to work in others circumstances.

Do you have any clues on the matters ?

  • You can run v.clean in the Processing Toolbox. This should solve most bad geometries issues. – ArMoraer Feb 18 '16 at 20:23
  • looks like a donut polygon so you need to cut (intersect) both side of the polygon. – Mapperz Feb 18 '16 at 21:16

You can generate a 1 by 8 grid with bounds set to the bounds of you polygon. Then clip your polygon with the cells of this grid. The product would be eight equally proportioned sections of the original polygon.

  • As an afterthought is may be necessary to split the grid cells into separate files before the clip to achieve the desired results. – Kingfisher Feb 19 '16 at 14:30
  • Kingsicher, i tried your solution. I must admit that im not familliar with these functions. I decided to take an easier way wich is to simply « intersect » the polygon. However, i was not aware of the possibility to use grid cells. I will most certainly use it soon. Thank you for your time. – Laurent Robitaille-Lainesse Feb 19 '16 at 20:31

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