|dataset||CityJSON v2.0||CityGML-XML v3.0||textures||details||compression|
|3DBAG||7.0MB (download)||40MB (download)||none||Buildings in LoD 0, 1.2, 1.3, 2.2; multiple attributes||5.7X|
|Den Haag||2.7MB (download)||19MB (download)||none||'Tile 01', Buildings (in LoD2) and Terrain are merged||7.0X|
|Montréal||5.6MB (download)||53MB (download)||none||Tile 'VM05'. Buildings in LoD2||9.5X|
|New York||110MB (download)||682MB (download)||none||Tile 'DA13'. Buildings in LoD2||6X|
|Railway||4.5MB (download)||39MB (download)||[ZIP]||CityGML demo. Buildings, Railway, Terrain, Vegetation (with Geometry Templates), Water, Tunnels||8.7X|
|Rotterdam||2.7MB (download)||18MB (download)||[ZIP]||Neighbourhood 'Delfshaven'. Buildings in LoD2||6.7X|
|Vienna||5.6MB (download)||40MB (download)||[ZIP]||Buildings in LoD2||7.1X|
|Zürich||293MB (download)||2100MB (download)||none||Buildings in LoD2||7X|
Observe that the file size doesn’t take into account the size of the textures files (PNG, JPG, etc) since CityJSON refers to the same ones.
CityGML-XML files have all the carriage returns, tabs and spaces removed (with this script), for a fair estimation of the compression factor.
CityJSON files do not contain CR or spaces or any formatting.
This very nice study (evaluation of file formats in the context of geo-referenced 3D geometries) compares several file formats for 3D geometries, with a focus on geographical datasets.
The outcome is that CityJSON is nearly as compact as much simpler formats (OBJ, STL, OFF), and it still allows different CRS, textures, complex attributes, complex geometries, etc.
The summary graph is particulary nice, click to get an interactive graph!