Feature request #8043

Avoid duplicate nodes from "Extract Nodes"

Added by magerlin - about 11 years ago. Updated almost 8 years ago.

Pull Request or Patch supplied:No Resolution:wontfix
Easy fix?:No Copied to github as #:16885


When extracting nodes for a polygon it appears that "Vector", "Geometry Tools", "Extract Nodes" outputs the same point twice as both a starting point and an ending point for the set of lines constructing the polygon. Perhaps this is just to follow the OGC Simple Features Specification?

But the practical use of this rather random duplicate point is hard for me to see (except perhaps for some error testing).

So I suggest to either simply not output the last and duplicate point or to make the user able to select whether he wants it or not.

See more here: http://osgeo-org.1560.x6.nabble.com/Duplicate-Points-from-Extract-Nodes-td5059332.html#a5059632


#1 Updated by Alexander Bruy about 8 years ago

  • Resolution set to wontfix
  • Status changed from Open to Rejected
  • Category changed from Vectors to Processing/QGIS

According to OGC specifications polygons should end at the same point as they started, IMO there is no issue here.

#2 Updated by Anita Graser almost 8 years ago

In the expressions we now have nodes_to_points which allows the user to specify the desired behavior:

nodes_to_points(geometry, ignore_closing_nodes)

geometry: geometry object
ignore_closing_nodes: optional argument specifying whether to include duplicate nodes which close lines or polygons rings. Defaults to false, set to true to avoid including these duplicate nodes in the output collection.

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