I am using QGIS (version: 3.28) and I am looking for a way for an automatic spatial generalization of polygons:

  1. Step: Merge adjacent polygons of same class (e.g. class "Grünfläche")

  2. Step: Polygons of class "Grünfläche" that are smaller then e.g. 0.3 ha should be merged with the adjacent polygon of another class, that has the longest "common boarder" with that polygon "Grünfläche". In other words: If a small polygon "Grünfläche" has a longer boarder with polygon of class "Landwirtschaft" and a shorter border with the polygon "Siedlung" --> the polygon "Grünfläche" should become "Landwirtschaft" and merge with the adjacent polygon "Landwirtschaft"

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  • Have a look at Eliminate Selected Polygons.
    – ahmadhanb
    Jun 19, 2023 at 9:19
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    – Ian Turton
    Jun 19, 2023 at 10:22
  • You might want to post some sample data Jun 19, 2023 at 13:02

1 Answer 1


Step 1: Run Dissolve, using Class as the Dissolve field, and Keep disjoint features separate flag checked.

Step 2a: Use Field Calculator to add an Area field, to get the area in hectares.

Step 2b: Select all polygons with Area < 0.3 ha using Select by expression.

Step 2c: Use Eliminate selected polygons with Largest Common Boundary as the merge criterion.

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