CityJSON

[tidoust]

CityJSON is a format for encoding a subset of the CityGML data model, an OGC standard, using JSON. A CityJSON file represents both the geometry and the semantics of the city features of a given area, e.g. buildings, roads, rivers, the vegetation, and the city furniture.

The proposal is driven by Hugo Ledoux (@hugoledoux), working at Delft University of Technology.

See:

• Presentation slides that describe the rationale for the proposal and comparison points with other formats such as GeoJSON, TopoJSON, and of course CityGML
• GitHub repository tudelft3d/cityjson
• Minutes of CityJSON discussions during the Spatial Data on the Web IG F2F in Amersfoort, 20 February 2018.

[tidoust]

For reference, CityJSON update, 9 March 2018

[hugoledoux]

Progress

• the discussions we had during the Fort Collins meeting about the links to CityGML-SWG (ie having implementation + code part of the standard, and not just the abstract data model; offering profiles in the future; key concepts in draft CityGML v3 that would make the implementation of the data model very complex, etc.) triggered some discussions in that group, to say the least. The CityGML-SWG is going through an "examination of conscience" this summer, which will have impacts on what CityJSON will be in the future. Right now the chairs of the SWG are designing a plan, and I am eagerly waiting to see what that plan contains. Thus, I can't say much at this point.

• working on CityJSON v0.7:

  1. better metadata for 3D data (based on a subset of ISO19115) are being added
  2. CityJSON has a draft proposal for Extensions (known as ADEs in CityGML). http://www.cityjson.org/en/latest/extensions/

• improved the python software cjio to process CityJSON files.

Next steps

• working on handling large files (https://github.com/tudelft3d/cityjson/issues/6)
• (large files would be the 'last' item that is needed to have a complete standard IMO. All is in draft and can change, but with large files splitting/tiling then all aspects would be covered)

[hugoledoux]

Progress

• CityJSON v0.8 released
• Extensions to the core model are now supported (https://www.cityjson.org/en/0.8/extensions/)
• software cjio supports v0.8 and allows to manipulate/edit CityJSON files

Next steps

• development of the specs (fixing inconsistencies + improvements) and of the software (cjio, azul, etc.) will continue.
• Because the OGC CityGML-SWG is going through a crisis at the moment, CityJSON standardisation will be put on hold for a while. The slides explains better the issue: https://www.dropbox.com/s/xwkt9qqbra1ty8w/2018-10-22-w3c-cityjson.key.pdf?dl=0

[tidoust]

The Spatial Data on the Web IG resolved to move the issue to the parking lot given the lack of immediate standardization plans for CityJSON.

[akuckartz]

CityJSON should be based in JSON-LD.