map: small polygons yellow

attribute table

Does anybody know a solution for this qgis task?

I have a polygon layer with many small and bigger polygons. I would like to merge/dissolve the polygons smaller than 100 m² with directly adjacent (bigger) polygons, in the following way:

only the polygons smaller than 100 m² shall dissolve with a bigger polygon, only if both have partly a common border . In the example "test layer", I uploaded, only the small polygons with fid 1 and 2 shall dissolve with the biggest adjacent polygon. (in the uploaded map the small polygons are yellow) The other small polygons 18 and 20 shall not dissolve with another polygon, because they do not join directly to another polygon. The attributes shall be taken of the bigger polygon (see uploaded attribut table).

Does anybody have an idea?

1 Answer 1

  1. "Select by expression" $area<100 (or "area"<100 if you want to use your area field)
  2. "Eliminate Selected Polygons":

This algorithm combines selected polygons of the input layer with certain adjacent polygons by erasing their common boundary. The adjacent polygon can be either the one with the largest or smallest area or the one sharing the largest common boundary with the polygon to be eliminated

  • 1
    thanks a lot! "Eliminate selected Polygons" is exactly the algorithm I need!
    – Bertram
    Jan 16, 2022 at 7:43

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