OpenStreetMap
Hey, i want to calculate the area of trees in a city (Zürich, Switzerland), but when i do this (Python or QGIS) the result is 0. When you take a look on the map, there are many trees found with “natural=tree”. How does the calculation of Nodes work? And what is the area of the tree that is calculated - only the trunk? And maybe it’s just a really small number that the output is 0? Thanks for your help.
Discussion
Comment from mariotomo on 30 May 2022 at 21:03
a tree is a node, and a node is a mathematical point, with no area. have a look at the taginfo page for https://wiki.openstreetmap.org/wiki/Tag:natural=tree, you will see that some trees (1.3% of the total) have a diameter_crown value, which is very likely what you need. but 1.3% will probably not help you much. you might infer the diameter_crown from the species and the height, but that’s probably a huge lot of work. I guess you need to think further on what you want to achieve related to what information you have.
Comment from mmd on 31 May 2022 at 10:11
https://help.openstreetmap.org/questions/84625/calculation-of-area-of-nodes-in-osm has some more ideas (duplicate post by OP)