CityJSON/io: Python CLI to process and manipulate CityJSON files
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cjio, or CityJSON/io

License: MIT

Python CLI to process and manipulate CityJSON files. The different operators can be chained to perform several processing operations in one step, the CityJSON model goes through them and different versions of the CityJSON model can be saved as files along the pipeline.


It uses Python 3.3+ only.

To install the latest release:

pip3 install cjio

To install the development branch, and still develop with it:

git checkout development
virtualenv venv
. venv/bin/activate
pip3 install --editable .

Alternatively, you can use the included Pipfile to manage the virtual environment with pipenv.

Note for Windows users

If your installation fails based on a pyproj error there is a small hack to get around it. You can download a pyproj wheel (binary of a python package) based on the python version you have installed. A good website to use is here. You then run:

pip3 install [name of wheel file]

You can then continue with:

pip3 install cjio


After installation, you have a small program called cjio, to see its possibities:

cjio --help

  assign_epsg                Assign a (new) EPSG.
  compress                   Compress a CityJSON file, ie stores its...
  decompress                 Decompress a CityJSON file, ie remove the...
  export                     Export the CityJSON to an OBJ file.
  info                       Output info in simple JSON.
  locate_textures            Output the location of the texture files.
  merge                      Merge the current CityJSON with others.
  remove_duplicate_vertices  Remove duplicate vertices a CityJSON file.
  remove_materials           Remove all materials from a CityJSON file.
  remove_orphan_vertices     Remove orphan vertices a CityJSON file.
  remove_textures            Remove all textures from a CityJSON file.
  reproject                  Reproject the CityJSON to a new EPSG.
  save                       Save the CityJSON to a file.
  subset                     Create a subset of a CityJSON file.
  update_bbox                Update the bbox of a CityJSON file.
  update_textures            Update the location of the texture files.
  upgrade_version            Upgrade the CityJSON to the latest version.
  validate                   Validate the CityJSON file: (1) against its...  

Pipelines of operators

The 3D city model opened is passed through all the operators, and it gets modified by some operators. Operators like info and validate output information in the console and just pass the 3D city model to the next operator.

$ cjio example.json subset --id house12 info remove_materials info save out.json
$ cjio example.json remove_textures compress info
$ cjio example.json upgrade_version save new.json
$ cjio myfile.json merge '/home/elvis/temp/*.json' save all_merged.json

Validation of CityJSON files against the schema

To validate a CityJSON file against the schemas of CityJSON (this will automatically fetch the schemas for the version of CityJSON):

$ cjio myfile.json validate

If the file is too large (and thus validation is slow), an option is to crop a subset and just validate it:

$ cjio myfile.json subset --random 2 validate

If you want to use your own schemas, give the folder where the master schema file cityjson.json is located:

$ cjio example.json validate --folder_schemas /home/elvis/temp/myschemas/

Example CityJSON datasets

There are a few example files on the CityJSON webpage.

Alternatively, any CityGML file can be automatically converted to CityJSON with the open-source project citygml4j.