In the last few weeks, I have discovered different ways to retrieve the center line of a polygon in QGIS. I am working on an urban Digital Twin. On this project I am focussing on adding more detail to city by converting 2D points to 3D objects. The government of the Netherlands provides us with open datasets. These open datasets contain vectordata and can be edited to your liking. The vectordata forms the basis of georeferenced 3D objects.
The first iterations of the workflow had two major drawbacks. Firstly, these iterations contained many repetitive operations. This disadvantage can be absorbed by using the model designer in QGIS. Secondly, these iterations were far too reliant on plugins from third parties.
Objective
By using two algorithms in QGIS I have succeeded in extracting vertices from a polygon based on the value of an attribute. Now I am aiming at retrieving the centroid of the line or the buffer between the vertices of the polygon. This centroid can then be used to draw a centerline in the polygon. An additional advantage is the loss of unwanted artifacts, which occur in the Chordal Axis algorithm of the Geo Simplification plugin.
Issue
At the moment, I am stuck in choosing the right algorithm for the operation. After searching different forumposts I found some interesting strategies:
- Creating road center line from Grid-Polygon Shapefile using QGIS
- Creating middle line between two lines in QGIS
- Finding centrelines from polygons in QGIS
Example
In QGIS I have managed to presentate the vectordata as follows. The orange line visualizes the Chordal Axis algorithm of the Geo Simplification plugin. The green vertices should be used in the desired workflow to extract the centroid between those vertices.
Desired solution
A workaround where the centroid between the green vertices is being used to model a centerline. This workaround should eliminate the 'triangle lines' at the end of a polygon.
I would highly appreciate your input on my workflow and look forward to hearing from you at your earliest convenience.
