Close small gaps between line geometries with QGIS automatically

Question

I have a vector layer which contains about ~4000 line geomtries. Between some of them are tiny gaps, sometimes just centimeters. Instead of manually adjusting the gaps I hope that there is a tool, which snaps dangling endpoints of line geometries to the closest nagling neighbor, with a specified distance.For example, as in the image, the gap between the lines is just 0.007m, but I will need to further process them and for it, I would need to close the gap between them.

Is there a tool in QGIS, with which I would be able to close those gaps by snapping endpoints within a specified distance?

It is not the first time I came across this problem and, again, end up, with not finding a solution myself.

Answer 1

Ok so you're talking about snapping, and there are a couple of solutions. But if you want to avoid having to correct them in the first place (prevention is better then a cure after all), at the start of the project in QGIS before you start digitizing check that snapping is enabled by default go to the 'Setting' menu → 'Options' and look for the 'Digitizing' tab. Here under the section 'Snapping' you can define the parameters as needed. If it's not you that is creating the geometries maybe share this with the person who is - it'll save everybody some time in the long run.

Otherwise, if you need to correct existing geometries you need to basically do what John has already suggested in the comments. In the first instance try just using the 'Snap geometries to layer' tool in the processing toolbox.

EDIT : I forgot to mention you can access the snapping parameters (for when you're digitizing) from a toolbar :

Answer 2

UPDATE: I strongly advise to use the v.clean tool. With the tool 'Snap geometry to layer' I had the problem that it creates invalid geometries.

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Easier than the v.clean tool (as described below) is the 'snap geometries to layer'-tool: To create a new layer (not to modify your objects directly), when you use the search bar, select the algorithm under 'Processing Algorithms'. Setting a snapping of 1m you specify it accordingly:

This will create a new layer in which the gaps are eliminated.

There is aso the v.clean-tool. However, the tool looks a bit intimidating regarding all the options and parameters to be set. For me it worked to clean the gaps by setting the Input feature type to 'line', as Cleaning tool I selected 'break' and 'snap', and (this is very important) under the 'Threshold(comma separated for each tool)'-option, I set the snapping distance. So here it is 1m and as I use two tools (snap and break), I will define this here as 1 for break, and 1 for snap --> 1,1. Further you will need to set the extent to the layer ('Calculate from layer'). All other parameters I let on default.

The output from this tool is great, as you now only get the corrected layer but also a layer whith only the corrected lines, so can see, which lines have been corrected. This is actually pretty nice!