qgis – How to Snap Two Line Vertexes in Different Layers in QGIS

postgispostgresqlqgisqgis-pluginssnapping

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I want to snap between two poly-lines from 2 different layers (Layer1 in Brown and Layer 2(postGIS layer) in Pink color- ), but my snap option don't work. I have changed the tolerance to different levels but still not getting the results.

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I don't get the magenta + sign to appear near vertices for snapping as many say it online.

Which tool used for snapping? I know only the "Node tool" which is not working .
I have set both layers editable (toggle editing set: ON)
Is there any better plugins there(I have tried many available ones.)?

Please give me suggestions since I am a beginner in QGIS.

Best Answer

On your first picture no 'Enable Snapping' options... Make settings as shown below:

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Related Solutions

QGIS Snapping – QGIS Not Updating Some Snapping Options from Python: How to Resolve

If you want to update the options you see in Settings > Snapping Options..., you can use the setSnapSettingsForLayer() function from the QgsProject Class:

proj=QgsProject.instance()
layer = qgis.utils.iface.activeLayer()
proj.setSnapSettingsForLayer(layer.id(), True, 0, 1, 10, True)

Note that although you're using the active layer to set the snapping options, this will apply to all layers in your project.

Interestingly, your method does not update any GUI options in Settings > Options > Digitizing > Snapping nor in Settings > Options > Advanced> Qgis > digitizing. But if you use the following, these GUI options will be updated but not in Settings > Snapping Options:

from PyQt4.QtCore import QSettings
QSettings().setValue('QGIS/digitizing/default_snap_mode', 'to vertex and segment')
QSettings().setValue('QGIS/digitizing/default_snapping_tolerance', 10)

But I'm not in a position to say whether or not it's a bug.

EDIT:

I am also using QGIS 2.14.3-Essen for Win7 64-bit.

I did some more testing also, it seems that for me atleast, the Settings > Snapping Options... interface only gets updated when I either use the setSnapSettingsForLayer class or close the interface and open it again. This includes testing the checkboxes the same way you have done.

Therefore, if you want to use the advanced snapping options, try:

proj = QgsProject.instance()
proj.writeEntry('Digitizing', 'SnappingMode', 'advanced') 
layer = qgis.utils.iface.activeLayer()
proj.setSnapSettingsForLayer(layer.id(), True, 0, 1, 30, True)

Note that you will need to select each layer and run the last 2 lines to update the settings in the advanced interface.

It seems that the setSnapSettingsForLayer class only registers when using the advanced snapping options because if you use the following for either current_layer and all_layers, any values set using the setSnapSettingsForLayer class seems to be ignored but the interface will be updated with the values you set using proj.writeEntry():

proj = QgsProject.instance()
proj.writeEntry('Digitizing', 'SnappingMode', 'all_layers') 
proj.writeEntry('Digitizing','DefaultSnapTolerance', 25.0)
layer = qgis.utils.iface.activeLayer()
proj.setSnapSettingsForLayer(layer.id(), True, 0, 0, 0, True)

Because now if I type the following like you have done:

>>> proj.readNumEntry('Digitizing','DefaultSnapTolerance')
25

Weird behavour...

[GIS] Using ‘Split Features’ tool to split a polyline at a specific node with QGIS

Normally, I use snapping option of 10 pixels and it works perfectly, as you can see below:

Using Split feature tool with the above snapping option after selecting the feature that you want to split, the snapping and splitting works as expected:

The pink (+) mark is the snapping at the vertex location.

Best Answer

Related Solutions

QGIS Snapping – QGIS Not Updating Some Snapping Options from Python: How to Resolve

[GIS] Using ‘Split Features’ tool to split a polyline at a specific node with QGIS

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