Finding centre line of irregular polygons with QGIS?

Question

I have a set of irregular and curved polygons which I would like to find the centre line of them. I've found some solutions for this problem such as Voronoi polygons but It doesn't work for me. It generates a zig-zag line with too many vertices. I used another solution creating centre lines joining the middle vertices from the short sides but it works well for straight polygons only but not for curved polygons. Adding points along the centre lines with QGIS

Ideally, I would like a simple central line for each polygon with 2 vertices only. Either using QGIS/Graphical Modeler or Python. My target is adding points to the centre line every 3 metres, as you can see on the image.

Answer 1

Try Thin greyscale image to skeleton plugin:

The Thin Greyscale plugin will thin a greyscale image to a greyscale skeleton image, given a set of levels

1. Convert polygon to raster with Rasterize
2. Run Thin greyscale image to skeleton plugin
3. Convert to polyline using GRASS r.to.vect