I have a bit too complex multipolygon set to be used in a web application (thematic map) so I'd like to simplify the structure by removing small islands of areas. I am not an expert on QGIS but so far I have managed to split the multipolygons into simple polygons and calculate the areas of each. I just can't remove all the islands less than some size, as some areas have bigger secondary islands than main polygon of other areas.

So I thought that the best solution would be to remove all but biggest polygons of each area. Only I haven't been able figure out or search the solution from Google how to do it on QGIS. Is there a way to do it?.

A secondary thought: There are a few areas with holes (meaning another area inside the bigger one), does my intended protocol break these holes as well?

wbr hank


From the Processing Toolbox, search for and run the "Keep n biggest parts" algorithm. If you set "To keep" as 1, you'll only get the largest part in the output.

  • 1
    Thank you very much. The QGIS toolbox is quite big, didn't see that
    – hank
    Apr 26 '18 at 6:24

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