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I'm using QGIS 2.8 to modify a line. I need to add a point on one end of this line, and then move this new point further away, leaving the original end point in the same place.

I can manage to create a new point at the end of the line by:

  • entering Settings > Snapping options
  • setting "Snap to" "To Vertex"
  • setting a "Tolerance" that's > 0
  • selecting the layer and clicking "Toggle Editing"
  • selecting the "Node Tool"
  • double clicking on the end of the line

And here's the problem. When I try to move the point I just created, I move the old line end instead.

Here's what happens, in pictures.

Basic line New point on one end Wrong point moved

I want the old line end to stay there, untouched (same coordinates as before), while I want the new point I added to be moved. Instead, the opposite is happening.

3 Answers 3

15

What you seek can be done easily using the digitizing tools plugin.

The plugin adds a new toolbar with a couple of new tools.

enter image description here

The tool you need for this task is the amend lineenter image description here.

It get active when you turn edition mode in a line layer. And you use it by clicking the begin or end vertex of a line and then keep clicking for new vertex. To finish, you rigth click.

enter image description here

Update - fast-forward to 3.10 LTR

In most recent versions of QGIS, you no longer need a plugin to do this operation. The native edit nodes tool allows extending the line:

  1. Click the small plus (+) sign.
  2. digitize the new vertex
  3. Right-click to stop digitizing

enter image description here

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  • In QGIS 3.10 it looks like there is no amend line or edit line tool in the digitizing tools that works like you show. I can use the vertex tool, but it is cumbersome requiring a double click, then move cursor to where you want the line extended to, then click to place new vertex where wanted to extend line. If anyone knows of a tool now like the tool demonstrated above please let us know where to find it in 3.10.
    – JJD
    Feb 8, 2021 at 2:19
  • @JJD Check the update. It's easier than you describe. Feb 11, 2021 at 0:47
  • Alexandre, Thank you for the update!
    – JJD
    Feb 12, 2021 at 8:30
  • 1
    @AlexandreNeto: I think you mean "3. right-click to stop digitizing" Feb 16, 2021 at 12:43
1

The Node Tool can be a little difficult to handle, and can give random results when dealing with end points. You are following the correct procedure, but sometimes the new point seems to be created "under" the old one (it just happened to me).

Just try again and maybe try to change the zoom level. It should work eventually.

0

Make sure to increase the Preferences/Digitizing/Search Radius Vertex Edits to at least 10 pixels.

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