[GIS] Automatically adding nodes to vertices on lines using QGIS

linenodesqgisroadvertices

I'm currently using QGIS 2.17 to process map data and for drawing roads. I'm trying to add nodes whenever a road breaks, turns or starts/ends.

I've tried using the plugin "Locate points among lines" but it has one error : it adds a node to both a start and end of a road point instead of linking it with the next road point, which means I've got 1 extra node on each start and end of road to delete.

(A road "breaks" whenever it reaches an intersection/pedestrian crossing, and a new road linked directly with the previous road starts.)

Basically I want to do this:
O–>O———>O instead of this OO—–>OO———->OO

Is there a way to automate this process?

Best Answer

QGIS 3

Use the "Split with lines" tool from the Processing Toolbox (Ctrl+Alt+T).

QGIS 2

You can use "Split lines with lines tool" in QGIS from Vector overlay Tools > Split lines with lines to add node when two lines get connected together. The input line file can be the same file for input layer and split layer, as you can see below:

After running the "Split lines with lines" tool and use same file for input layer and split layer, as you can see below:

The output will be like this:

The "Split lines with lines" tool can be found in the Processing Toolbox:

Related Solutions

QGIS – How to Automatically Add Vertices to Lines Every X Meters

in Qgis 1.8.0 there is a densify function but i don't know if it has distance parameter like in Arcgis

QGIS – How to Split All Lines in Layer at Vertices

Try the "Explode lines" from the Processing Toolbox (Ctrl+Alt+T) will split all lines at their vertices to separate lines.

Menu Processing -> Toolbox. Type "explode" into the search field to find the function. Select your line layer from the dropdown and start. This will produce a new layer.

Selecting one or more lines from the line layer will produce a splitted layer with only these features, discarding the rest.

Note: As QGIS is moving fast, all infos below are outdated already.

I think Explode lines would be the the noob-solution through the SEXTANTE toolbox. QGIS Geoalgorithms > Vector geometry tools > Explode lines. Unfortunately, it does not seem to work at the moment, i get an error message only.
Traceback (most recent call last):
  File "path/.qgis//python/plugins\sextante\core\GeoAlgorithm.py", line 145, in execute
    self.processAlgorithm(progress)
  File "path/.qgis//python/plugins\sextante\algs\Explode.py", line 58, in processAlgorithm
    features = QGisLayers.features(layer)
NameError: global name 'layer' is not defined
A working solution is the Split Feature-Plugin from the "contributed" repository, which does the job for me.

In general I prefer sextante functions over separate plugins, cause the workflow with sextante is so much faster and produces no junk-files of intermediate steps (provided it works).

EDIT: Unfortunately, a lot of plugins were not moved to the official plugin repository yet, but are still only available through the "contributed" plugin repository: http://pyqgis.org/repo/contributed, which was removed from the default repositories list with version 1.8.

There you can download them individually and unzip them in your .qgis/python/plugins folder OR you add this address to your plugins repository list: Plugins -> Fetch python plugins -> Tab "Repositories" -> Add ... -> enter a name and the url.