QGIS 3 – Creating Nested Hex Grids for Advanced Cartography

Question

I'm looking to replicate the kind of map seen here, where there are essentially multiple hex grids nested inside one another.

Author : Kate Berg

That example was made in ArcGIS Pro, whereas I'm working in QGIS 3.20. I have gotten as far as creating a couple of separate hex grid layers and tried tinkering with the offsets of the top layer. However that only moves the top layer and doesn't have the shrinking effect I'm after.

Answer 1

Step 1. Create a grid with the "Create grid" geoalgorithm

Step 2. Use the "Geometry by expression" from the Processing Toolbox (Ctrl+Alt+T).

With the following expression:

make_regular_polygon(
    centroid($geometry),
    end_point(
        line_substring(
            make_line(
                point_on_surface(
                    boundary($geometry)
                    ),
                centroid($geometry)
                ),
            0,
            0.25 -- specify a step here 
            )
        ),
    6,
    0
    )

and get the output:

In case if more hexagons are required apply the following expression:

collect_geometries(
    array_foreach(
        generate_series(
            0,
            distance(centroid($geometry), point_on_surface(boundary($geometry))),
            0.25 -- specify a step here
            ),
        make_regular_polygon(
            centroid($geometry),
            end_point(
                line_substring(
                    make_line(
                        point_on_surface(
                            boundary($geometry)
                            ),
                        centroid($geometry)
                        ),
                    0,
                    @element 
                    )
                ),
            6,
            0
            )
        )
    )

and get a corresponding answer:

Keep in mind that each output feature is a MultiPolygon, so the application of the "Multipart to singleparts" tool can be useful.

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References:

• Changing polygon circles to hexagons using QGIS