Trees in Vienna
Vienna tree register: what it knows, and what is visible from the air
The City of Vienna tree register lists the city’s own trees, along streets and in parks. Trees in gardens and courtyards, and trees of other owners, are not in it. The BEV laser scan (surface minus terrain, 1 m grid) shows every tree with its height and crown, there too. The map shows both for two areas of one square kilometre each, and how they fit together: the register stays the basis, the laser scan adds every tree with no register trunk in its crown.
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Shows 700 × 700 m around the address. Or pick one of the two sample areas:
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Aerial photo: City of Vienna, City of Graz, basemap.at (CC BY 4.0)
Cottage quarter · Währing and Döbling, villas with gardens
Share under tree crowns
What the laser scan alone misses: 177 register trees were planted after the flight (2023), and of 317 young trees (planted 2016 to 2022) it finds only 96, their crowns are too thin for the 1 m grid. Single circles cover 58 % of the crown area, so the area itself is drawn as well.
Wieden · Gründerzeit blocks, avenues and courtyards
Share under tree crowns
What the laser scan alone misses: 85 register trees were planted after the flight (2023), and of 142 young trees (planted 2016 to 2022) it finds only 45, their crowns are too thin for the 1 m grid. Single circles cover 51 % of the crown area, so the area itself is drawn as well.
Light green is the measured area under tree crowns, the circles are single trees at crown size. Tap a tree to see its values. Drag to move, scroll wheel or two fingers to zoom.
How a laser scan tree is made
- Surface model minus terrain model (BEV, 1 m) gives the height of everything standing on the ground.
- Buildings are removed (the city’s building model plus OpenStreetMap, 1 m buffer, courtyards stay), and so are tram and rail lines, so that overhead line masts do not count as trees.
- Whatever is still higher than 2.5 m is almost always vegetation. Two results: the crown cover as an area, and single trees, the top as a local maximum, the crown growing outwards from there.
- Masts, spires and smooth roof surfaces are removed by shape thresholds that sit at the edge of the values of confirmed trees.
How well it matches
Comparison of trees that are in both sources (one to one, at most 3 m apart), measured on tiles that were not used for tuning:
| Pairs | Position | Height | Crown | |
|---|---|---|---|---|
| Vienna | 12,349 | 1.1 m | 84 % within 2 m of the register class | 82 % within 2 m |
| Graz | 6,066 | 1.4 m | 1.6 m, no bias | 1.5 m, no bias |
| Linz | 9,290 | 1.4 m | 1.7 m, no bias | 1.6 m |
Medians. Graz and Linz record metres, but estimated ones; Vienna uses 5 m classes. Within a row of trees of the same species, a tree in the laser scan deviates only 0.8 m from the row average.
Combining both
Where a tree register exists, it is the basis: it knows the species, the planting year and young trees the scan cannot see yet. The laser scan adds height and crown for these trees and adds every tree with no register trunk in its crown, meaning the trees in gardens and courtyards.
The rule is deliberately narrow: if a trunk stands in the crown, the tree counts as known. Widening the search radius by another 3 m changes the number of added trees by only 3 to 11 %, so there is no hidden block of trees counted twice.
What you should know
- The flight year is not the file date. The BEV assembles the newest state per area: Vienna 2023, Graz 2024, Salzburg 2022, parts of the Vienna surroundings 2011/12. We only use flights from the last five years.
- Many flights are leafless. Then the beam passes through bare crowns: deciduous trees come out about 1.2 m too low and 1 m too narrow. We correct this per flight where the state is documented. Vienna 2023 was flown in leaf, nothing is corrected here.
- A scan sees crowns, a register counts trunks. Two trunks under one crown are one tree in the laser scan. For shade and greenery, the crown is the right measure.
- The species stays open. Deciduous or conifer cannot be read reliably from the crown shape; that needs a second source.
Data: BEV, ALS elevation grids DSM/DTM 1 m (CC BY 4.0), City of Vienna tree register (CC BY 4.0), City of Vienna building model (CC BY 4.0), streets and parks © OpenStreetMap contributors (ODbL). Analysis: wohnwahn.at, September 2026. Register crowns are drawn at the middle of their class. data.wien.gv.at