Creating polyline segments by points in maximum distance to each other along another polyline using QGIS

Question

I have

• a polyline layer contains different roads
• a point layer contains points along these roads with random distances between the points. The points are also listed randomly and not in order along these roads.

I want to connect with polylines the points along the roads which are close each other at a maximum (e.g. 35.0 m) or smaller distance. Any suggestion how to work these out?

The roads turn even to 180° at some points (as shown in the attached figure) and the distance between the roads can be smaller than 35.0 m.

My ultimate purpose is to get the road segments where the points are distant in maximum 35m.

I use QGIS version 3.10.1-A Coruña

Answer 1

STEP-1

I installed the plug-ins ‘Locate Points Along Lines’ and ‘LRS’ (Linear referencing System) and I followed the video [Linear referencing in QGIS 3 | burdGIS] (https://www.youtube.com/watch?v=meC3AfTOtps).

STEP-2

I used the first plug-in to calibrate the road-polyline layer

STEP-3

Then I used the Calibrate tab of the LRS, for the previously created temporary layer, to create the Routes temporary layer

STEP-4

I used the Measures tab of the LRS to locate my points (point layer) in sequence along the Routs layer I created before

STEP-5

I continued with the Step-3 of @Taras from my initial Question [Projecting polygons into polyline]Projecting polygons into polyline. In particular,

a) I used 'Points to path' and for ‘Order field’ I used the ‘measure’ field created at the previous step, while for ‘Group field’ I used the ‘route’.

b) I had also to ‘Explode’ the lines created (as in [Splitting all lines in layer at vertices using QGIS?] Splitting all lines in layer at vertices using QGIS?).

c) I added the length of the lines ([Calculating Line Lengths and Statistics (QGIS3)] https://www.qgistutorials.com/en/docs/3/calculating_line_lengths.html).

d) Then I was able to select those lines longer than my requirement (35.68m in my case) and to delete them (when at Toggle Editing) together with other unsuitable lines created.

e) Afterwards, I ‘Dissolve’ these lines into polyline segments in order to create the proper Buffers at the next step.

STEP-6

Then I was able to continue with the Step-4 of @Taras from my initial Question ([Projecting polygons into polyline]Projecting polygons into polyline) and to create the 'Buffer' by using 3.5m for ‘Distance’, Flat for ‘End cap style’, and Round for ‘Join style’ in my case.

STEP-7

Finally I applied ‘Intersection’ between the original polyline-roads layer and the Buffer layer from the previous step to get the polyline segments of my interest.

I had also to apply ‘Multipart to Singleparts…’ to have the segments as individual features at the layer’s Attributes.