Answers to: calculation of area of nodes in osmhttps://help.openstreetmap.org/questions/84625/calculation-of-area-of-nodes-in-osm<p>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. </p>enMon, 30 May 2022 17:18:14 +0100Answer by EdLoachhttps://help.openstreetmap.org/questions/84625/calculation-of-area-of-nodes-in-osm/84626<p>Nodes are points, so have no area.</p>
<p>For <a href="https://wiki.openstreetmap.org/wiki/Tag:natural%3Dtree">trees the wiki</a> mentions optional tags of circumference, diameter, and diameter_crown which you could use to calculate an approximate area.</p>
<p>Overpass suggests these are little used in Zurich (diameter_crown is on one tree note and three tree row ways for example). </p>
<p>There might also be larger areas tagged with landuse=forest or natural=wood.</p>EdLoachMon, 30 May 2022 17:18:14 +0100https://help.openstreetmap.org/questions/84625/calculation-of-area-of-nodes-in-osm/84626