I am really new with QGIS
I have a quadratic grid with different populations in each square and I have made polygons with the ORS plugin. The polygons cover some squares in full and some squares only partially. I need to count how much of the population is in each of the polygons. I am fine with assuming that the population is evenly spread within each square. I have tried to do that with MMQGIS, but I could not go further for my next step.
I am wondering if there is any other tool or way to do this. I hope to be able to do it automatically since I have to do it with lots of polygons.
Best Answer
This is a rather straightforward workflow heavily relying on the field calculator:
$area
in the field calculator (let's call this new fieldgrid-area
).$id
in the field calculator (fieldID
).intersect
, the first input being your polygons, the second your grid. This combines overlapping geometries and assigns them the attributes of both geometries.$area
of your intersected polygons (call it e.g.area-new
)."area-new"/"grid-area"
.pop-new
).pop-new
field and theID
, usingsum("pop-new","ID")
.dissolve
-tool your intersected polygons based on theID
-field.