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I have a layer with polygons and one with points at every vertices of polygon ( so I can label them with a number). I want to create a point at every new or modified vertex with virtual layer.

At the moment I use extract vertices and copy the new ones in point layer but I would like to do this automatically when a new polygon is created or modified.

Also if it is possible to generate only vertices that doesn't have a feature in point layer ( new vertices).

Is is possible to do this in Virtual Layer ? node_to_points(geometry) works but generates one feature with multiple points.

enter image description here

underdark
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tovidiu
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  • Welcome to gis.stackexchange! How do you assign vertex ids to the points? Are the ids randomly assigned? Do they have to be stable, i.e. when new polygons are added, the old ids are not allowed to change? Would you be open to a solution using database views? – underdark Sep 06 '20 at 09:46
  • Existing points have fixed ids( not random assigned), they are in another layer as points. The new points don't have to be fixed but have to differ from the point layer, maybe with a prefix like "D1, D2, D3 ....." and only where there is no point present at a vertex. In the picture above I managed to do that with virtual layers ... but the result is a multipoint feature at every vertex. I cannot use database views because I don't know how to filter features by project and user. I have many projects with different users and features in the same location. – tovidiu Sep 07 '20 at 14:52
  • If there is a way to filter by project and user in PostgreSQL tables it will be awesome.Thanks – tovidiu Sep 07 '20 at 14:52
  • Maybe have a look at the answers to this question as a starting point for what are looking for: https://gis.stackexchange.com/questions/381187/convert-vertices-of-polygon-features-to-points-using-virtual-layer-in-qgis – Babel Dec 21 '20 at 13:14

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