Voronoi Diagram on a given polygon using QGIS

Question

I am trying to create a Voronoi Diagram on a specific polygon, but there is some issue when dealing with edges. Here is how I do it:

1. Preparing the points for Voronoi and the polygon for the diagram

2. Create Vornoi

3. Cut the edge using the polygon

4. Combine the cut Voronoi and the polygon using Union (not sure if this is the best way) And here comes my problem for the edges. I would like to: 1) remove the frame from original Voronoi map (marked in blue) 2) extend the edges to the edge of the area polygon(marked in red), so that the service area at the edge side will be realistic.

How can I do this?

Answer 1

You can use the v.voronoi tool from GRASS to create voronoi polygons, and it will enables you to specify an extent based on layer extent:

Answer 2

You can do this simply, by adjusting the buffer.

Here is an example. The following polygon and points layers would normally result in the problem you illustrate in your question.

1. When running the Voronoi polygons tool, increase the buffer region percent. The exact amount will vary, but since we're clipping the result, it won't hurt to overshoot. In my example, I use a buffer of 100% to double the extent.

Here is the output. My 100% buffer actually extends well beyond this image.

2. Clip the Voronoi polygons by the original polygon layer.

And there you have it!

Answer 3

In order to show you the variety of ways to solve your problem, only with the help of QGIS I will provide another way: initial data are presented in the screenshot below

1) Since your shape has a complex shape, run the “Vector> Geoprocessing> Buffer Zones” buffer onto it and extract the “Vector> Geometry processing> Eject nodes” points, see the figure below

2) Copy the points from the source layer “Pencil> Edit> Copy Objects” to the buffer points and run on them polygons Voronoi “Vector> Geometry Processing> Voronoi Polygons ...”, see the figure below

3) Cut the polygons with your original shape using "Vector> Geoprocessing> Trimming" and see the result ...

I wish you success…