FlatCityBuf beta

FlatCityBuf is a new cloud-optimised format for 3D city models based on FlatBuffers and CityJSON.

Key Features

  • Zero-copy data access: Efficient memory usage without data copying
  • Fast deserialisation: 9-250× faster than existing formats
  • Compact storage: 10-30% compression compared to CityJSON
  • Memory efficient: Uses 2-6× less memory
  • Spatial and attribute indices: Enables efficient queries to retrieve partial data
  • CityGML compliance: Adheres to the established CityGML data model

Performance Benefits

FlatCityBuf demonstrates significant advantages over existing formats:

  • Compression: Achieves 10-30% compression compared to the already compact CityJSON format
  • Speed: 9-250× faster deserialisation performance
  • Memory: 2-6× less memory usage during processing
  • Partial data access: Efficient queries through spatial and attribute indexing

Software and Schemas

The schemas and accompanying software for conversion to/from CityJSON are publicly available at https://github.com/cityjson/flatcitybuf under a permissive license.

Hidemichi Baba FlatCityBuf: a new cloud-optimised CityJSON format. MSc thesis in Geomatics, Delft University of Technology. 2025.