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(1) I have a vector grid layer.

(2) I have a multipolygon layer. Each polygon has a specific type (in this case a vegatation type)

Now I want to get as an output the grid layer where each cell contains the type whose polygon (out of the vegetation - multipolygon layer) occupies the largest area.

Following figure shows the grid layer overlaping the multipolygon layer: Multiploygon layer overlaping by grid layer

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  • Sorry to ask but ... do you mean you want to calculate the main vegetation type per grid cell ? Your question's title is clear ... but not the rest imho ...
    – Snaileater
    Aug 20, 2019 at 14:52
  • Yes, I want to get the main vegetation type per grid cell.
    – obrob
    Aug 20, 2019 at 18:02

1 Answer 1

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Use QGIS DB Manager : Database / Database Manager / Database Manager then Virtual Layers / Qgis Layers.

Try a query like this one :

select grid.id,max(st_area(st_intersection(grid.geometry,vege.geometry))),vege.type
from vege, grid
where st_intersects(vege.geometry, grid.geometry)
group by grid.id

That should do the job ...

Adapt the query to your data structure if needed (columns namings) ...

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