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How can I create a multiple inner (negative) buffer of a polygon layer that starts from an initial distance and repeats n times at a fixed distance?

The result should be independent polygons. Ex: I would like to generate 10 independent interior polygons relative to a layer of polygon features, the first of them 30m apart, and then 9 more interior polygons 1m apart.

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    Hi David, welcome to GIS SE. Please not that this is an english-language site and all contributions have to be in english, otherwise the question risks to be closed/deleted. Use an automatic translation software if you have troubles writing in english. A solution to your problem is using negative buffers with Geoemtry Generator/Geomtry by expression.
    – Babel
    Feb 20, 2022 at 11:08
  • A diagram to explain what you want to achieve would be a valuable addition to your question. By independent, do you mean they are (30 and) 1 m strips, or are they progressively getting 1 m wider, but all starting at the boundary?
    – Matt
    Feb 20, 2022 at 23:08

1 Answer 1

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  1. Use Menu Processing > Toolbox > Geometry by expression with this expression:
   collect_geometries (
       array_foreach (
           generate_series (30,39,1),
           buffer ($geometry, -@element)
       )
   )
  1. Run Menu Vector > Geometry tools > Multipart to singleparts:

Remark: Line 3 in the above expression contains the distances for the bufers: 30 is the initial distance for the first buffer; 39 is the distance of the last buffer (from 30 to 39, you get 10 elements), 1 is the distance between each buffer (here, for the value of 1, this is optional).

The solution, here demonstrated with Geometry Generator: enter image description here

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