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.
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.