We can do a quick scan of the green roof potential in the city by overlaying the flat roofs layer on a near infrared image.
1. Make sure the flat roofs layer is on top of the near infrared aerial photograph.
2. Go to the Layer Styling panel and make sure that the flat roofs layer is active.
3. Change the renderer from Single Symbol to Inverted Polygons.
In this way you style everything outside of the polygons.
4. Choose a white fill.
Now you can see which roofs are red and already have vegetation and which roofs are grey and could be turned into green roofs.
