I have a a layer of Voronoi areas. I would like to know the area for every polygon. What I have done is the following, but the numbers seem strange (negative numbers are there).
So, I do the following:
- Right click on Voronoi layer
- Click "open attribute table"
- Click on "edit mode"
- Click on "open field calculator"
- Choose "decimal number"
- Choose "create new field", give name "surface"
- in the expression box type "$area"
But I'm not sure the process is right. Where does it get the polygons from? I don't see any geometry in that... which leads me to believe it's calculating something weird.
The attribute table only has the lat/long of the point that the Voronoi algo uses to calculate the polygon. But I don't know where the polygon itself is.
Is that what I'm getting wrong?