Comparing overlapping features using Field Calculator in QGIS

Question

I have a building dataset and I am trying to perform a spatial analysis, to determine which building should be developed as a 3D model, for a mapping project.

Because in some areas the building density is too high, I have created a Ranking Matrix, so in the case that the buildings are too close from one another, the one with the higher rank will be chosen. And if the rank is the same, the one with the larger footprint will be preferred.

Can anyone suggest how the formula inside the Field Calculator should look like, so it would perform this analysis? I have tried many iterations and I can't seem to figure this out.

I would like the end result of this analysis to be another field, with 1 and 0, for suitable/not suitable for 3D development.

https://ibb.co/KDbMb8C

UPDATE: the features I want to compare are 100m buffers of the above mentioned buildings. So if the 100m buffers overlap, I want to compare the ranks of the two (or more) overlapping features. If the ranks are different, I want the formula to update the attribute table with '1' - for the suitable building. If the ranks are the same, I want to chose the building with the larger footprint and update that with '1', else, it should be '0'. Also, if there is no overlapping, those features should be also '1'

Answer 1

Create the buffer as separate layer - it should include the attribute field for rank. Then use this expression to generate the new boolean field to get a true/false value for which buildings to render in 3D (screenshot 1):

if (rank > array_max(overlay_intersects(@layer, rank)) or overlay_intersects( @layer) = false,1,0)

Edit

To include not only the distance and rank, but also the area (footprint) of the building, use this expression (you should have an attribute for the area of the building, create it with $area) - see screenshot 2:

case
    when overlay_intersects( @layer) = false then 1 -- no other building in the buffer-distance
    when rank > array_max(overlay_intersects(@layer, rank)) then 1 -- the buidling has the highest rank of all buidings withen the buffer-distance 
    when if (
        rank >= array_max(overlay_intersects(@layer, rank)) and 
        area > array_max (overlay_intersects( @layer, area)),1,0) then 1  -- the building has the same rank as another building inside the buffer-distance, but a larger area
    else 0  -- all other cases
end

Screenshot 1: Buildings in blue, labeled with their rank value. Buffers in pale yellow. Highlighted in light yellow the buildings selected with this expression using Select by expression:

Screenshot 2: includes also a condition about the area (footprint) of builings with same rank: