CityGML
The open exchange format for 3D city models. A digital twin published as CityGML can be used by someone other than the vendor who built it.
How this list is decided. Membership is not a field an editor set: it is every published entry whose own text names CityGML, matched at build time, with the sentence printed under each row so you can judge the match yourself. 3 entries in 3 cities.
✔ Every published entry is checked against the public sources it cites before publication.
Where it appears in the atlas
Berlin maintains a semantic 3D city model of some 550,000 LoD2 buildings in CityGML covering the whole 890 km² city.
The model is browsable by anyone through the city's 3D portal, handed out as CityGML for planning work, and carries a solar-potential tool that assesses roofs in three dimensions instead of two.
Helsinki 3D+ is the city's open 3D model of every building and the ground surface, combining a semantic CityGML information model with a high-resolution reality mesh, released as free open data in 2016 and licensed under CC BY 4.0.
Others in this group
The whole layer
Every standard, protocol and licence the atlas names, with the open-data licence ladder in one table: Standards & licences.