CityJSON (3D City Model)
Open BetaExport buildings to CityJSON 2.0 for 3D city modeling. Compact JSON format with vertex deduplication. Supported in 3DCityDB, QGIS 3D, ninja viewer.
Key Features
About CityJSON Format
CityJSON is a compact way of writing the same city model as CityGML, but in ordinary JSON instead of bulky XML. The same set of concepts (buildings, level of detail, attributes), only the file is many times smaller and is parsed by any language without special libraries. It is a recognized OGC community standard, not an amateur invention.
The format is chosen when a semantic 3D model is needed on the web, in scripts or in exchange between teams: to look at it in a browser viewer, to run it through Python, to put it into a repository, to hand it to colleagues without a heavy GIS stack.
The output is a single file: buildings at LOD1 detail are written as closed volumes extruded from OSM outlines. Vertices are stored as integers with millimeter precision through a scale factor and are deduplicated, so the file comes out noticeably lighter than the equivalent XML. The metadata records the coordinate system and the bounds of the model, and the buildings carry height, floor count and class.
What Program Opens CityJSON Files
The following programs and applications can open, edit, and work with CityJSON (3D City Model) (.city.json) files exported from OSM2CDR:
Format specifications
- Open standard
- 3D coordinates supported
- Lossless (no quality loss)
- Stores feature attributes
- Output: 1 file
- CityJSON 2.0 (OGC community standard). Lightweight JSON encoding of CityGML. Opens in QGIS plugin, ninja, FME.
Who Uses CityJSON Maps
How to Export CityJSON
How to Open After Export
- ninja (a free web viewer for CityJSON) — drag the file into the browser window and see the model at once; the fastest way to check the result.
- cjio (Python, free) — the command cjio file.city.json info shows statistics and checks the structure, while export converts the model into OBJ or other formats.
- QGIS 3 — CityJSON opens through the 3D view, convenient for looking at the buildings together with the flat layers of the map.
- Blender — import through the CityJSON add-on, if the model is needed for visualization rather than for computations.
- 3DCityDB and FME — accept CityJSON on a par with CityGML, if the model is headed for a city database.
Popular maps in CityJSON
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Frequently Asked Questions
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