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I'd like to have a polyline layer that has distance from the line origin inserted as marker points along the lines. The distances are stored in the attribute table as a field. The lines have directions.

Is there a plugin that can read the distances from the field, and create points along the lines for each record?

The context is a roads layer that will have maintenance distance markers from certain intersections. There are thousands of records and the road shapes are complex, not straight, so an automated process would be ideal.

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  • You can do it with PostGIS or Spatialite with postgis.net/docs/manual-2.0/ST_Line_Interpolate_Point.html. You must first find out the total length of the line with ST_Length so you can calculate the correct fraction to be used in Line_Interpolate_Point which means some planning and scripting.
    – user30184
    Nov 25, 2016 at 5:53
  • Maybe related: gis.stackexchange.com/questions/95017/…
    – AndreJ
    Nov 25, 2016 at 7:00
  • What about using the Extract nodes tool from the Processing Toolbox or Vector > Geometry Tools? This creates points at each vertex of the line. As you mentioned that the distances are stored in the attribute table, I assume the lines are broken into separate features with each having its length stored. In which case, you don't need to use distance to make the points, only the vertices. If you want to show which point goes with which line, you could run a spatial join such as the Join attributes by location tool.
    – Joseph
    Nov 25, 2016 at 11:26

3 Answers 3

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As Nelson Silva suggested I also use the LRS plugin. Additionally I use the "Locate points along lines" plugin to quickly create polyline end lengths used for LRS calibration process. enter image description here Once the LRS Calibration process is complete select LRS Events tab to load your attribute table with measured centerline distance to features. This example creates location points of roadway culvert crossings. enter image description here

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Both the QGIS-GRASS-Plugin and Processing ship the v.to.points-module. This should do what you are after. Not sure if the distance from the start node of each is written to the attribute table of the resulting points though... If not you might use the v.net-tools for that...

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you can use linear referencing with LRS plugin - https://plugins.qgis.org/plugins/lrs/

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