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I extracted vertices using 'Extract vertices' in Processing Tool. But so many unnecessary vertices extracted, so I want to remove them. What I want to leave is at the beginning and the end of the line. How can I remove those vertices in the middle of the line? I would like to know if there is a way to erase it all at once because there are so many things like that.

Vertices are in the same layer.

enter image description here

I want to remove all the blue vertices like the picture below.

enter image description here

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  • 1
    Can you please share a piece of your data with us?
    – Taras
    Dec 28, 2020 at 11:28
  • 1
    For instance here: wetransfer.com
    – Taras
    Dec 28, 2020 at 11:36
  • 2
    @Taras Thank you. Here is the shape file we.tl/t-WLoSZ2P7wt
    – jin
    Dec 28, 2020 at 11:41
  • 4
    If you remove the vertices of a curve, it will no longer be a curve, but a straight line, so you after representation is wrong.
    – Vince
    Dec 28, 2020 at 13:44
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    As Vince commented, you can't have just the endpoints and keep the shapes. If you want to keep your basic shapes but get rid of "unnecessary" vertices, then you could run the Simplify tool in Processing, or (my preference) the v.generalize tool in GRASS's Processing tools, if you have GRASS as part of your install. You can play with the tolerances to see how much shape change and vertice losses you are willing to accept.
    – John
    Dec 28, 2020 at 14:38

1 Answer 1

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From the QGIS Toolbox:

  • choose Extract specific vertices
    • in the Vertex indices field, specify the first and last vertex index as comma-separated list:
      0, -1

This will create a layer with the start and end vertices only, rather than excluding them from your result set.

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  • Thank you for answer but those lines are all made up of one, so if I extract the vertices like that, only two vertices are extracted..
    – jin
    Dec 28, 2020 at 11:25
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    The problem with your data is that all your lines are one single feature. You should first split somehow these lines to separate features - thus you should know what criteria to apply for splitting them. Maybe it would help to tell us what your final goal is, what you want to use these vertices for.
    – Babel
    Dec 28, 2020 at 12:22
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    Once you have your lines split, its easy to create start- and end points, see: gis.stackexchange.com/a/383032/88814
    – Babel
    Dec 28, 2020 at 12:31
  • @babel Thank you for comment. My goal is just to extract vertices at the line deflected or crossed.
    – jin
    Dec 28, 2020 at 17:07
  • As far as I see, this is not so easy as long as you do not manually create split lines. What does "deflect" mean? In the curve segments (exactly where you have many vertices to be deleted), the line always deflects. So in my opinion, it involves some manual work to create single lines. However, I still don't understand what you need these vertices for: as mintioned in other comments, you can't use them for a simpler line. If you would explain us more in detail what your ultimate goal is with these vertices, than maybe there is an easiere solution.
    – Babel
    Dec 28, 2020 at 20:41

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