In this project, I have three polygons, see the image below

  1. 'Polygons_From', includes input attributes, i.g. "Value_1", "Value_2", "Value_3", and $area for each quadrate (on the image there are two types of them).
  2. 'Polygons_To' polygons for which new values "Value_1_new", "Value_2_new", "Value_3_new" need to be defined
  3. 'Border' defines an area where the calculation should be done.


My task is to transfer values from 'Polygons_From' into 'Polygons_To' based on a certain aspect/ratio. Of course, I can simply achieve it with the 'Union' function as was suggested in this thread.

It uses $area-factor, but perhaps there are better approaches that will lead me to a much more efficient output?

So, I am asking for a recommendation regarding the technique/workflow that can be applied in QGIS 2.18. Shall I consider only $area or there are some other criteria?

Moreover, I looking forward to finding some papers that may improve my general understanding of the methodology.



1 Answer 1


Some 'Polygons_To' are in more than one 'Polygons_From' so you should decide to:

  • Duplicate polygons in 'Polygons_To' to match the number of intersections with the 'Polygons_From' layer. To do this You can use 'Join attributes by location' with one too many options selected.

  • Or use the Union tool from the 'Vector' menu to split 'Polygons_To' that intersect with more than one polygon in 'Polygons_From'.

Think it's also possible to list attributes of all intersecting layers into one column but haven't tried it yet.


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