I am new to QGIS and I have stumbled on this automatic way to map tree crowns using 4 points - north, east, south, west.
Most informative post was this and Solution 2 (8-vertex polygon).
The ellipse method works like a charm, but the drawn area is to vague for my purpose.
There I found code for exactly what I need:
make_polygon(make_line(
translate($geometry,0,max("N",0.2)),
translate($geometry,0.6*max("E",0.2),0.6*max("N",0.2)),
translate($geometry,max("E",0.2),0),
translate($geometry,0.6*max("E",0.2),-0.6*max("S",0.2)),
translate($geometry,0,-max("S",0.2)),
translate($geometry,-0.6*max("W",0.2),-0.6*max("S",0.2)),
translate($geometry,-max("W",0.2),0),
translate($geometry,-0.6*max("W",0.2),0.6*max("N",0.2)),
translate($geometry,0,max("N",0.2))))
Problem is that no matter what I try, output is still NULL. Even if I change NESW to numbers, its sill NULL. It should work, at least it has worked in the past for the person who wrote the code. Naming for NESW is correct. It was the first thing I checked.
I have a general idea how it should draw the polygon. That post was made few years ago. Has something changed?