CityJSON

.NET Standard 2.0 Library for reading and writing CityJSON files (https://www.cityjson.org/)

NuGet package: https://www.nuget.org/packages/bertt.CityJSON/

Dependencies

• NetTopologySuite

Sample code

Reading CityJSON file:

var json = File.ReadAllText("fixtures/minimal.city.json");
var cityjsonDocument = JsonConvert.DeserializeObject<CityJsonDocument>(json);

Writing CityJSON file:

var json = CityJsonWriter.Write(cityjsonDocument);
File.WriteAllText("output.city.json", json);

Or use the convenience method:

CityJsonWriter.WriteToFile(cityjsonDocument, "output.city.json");

Sample reading CityJSON 2.0 Seq file and converting to NetTopologySuite:

var cityJsondocuments = CityJsonSeqReader.ReadCityJsonSeq("./fixtures/cityjsonseq/paris_tower.city.jsonl");

Writing CityJSON 2.0 Seq file:

CityJsonSeqWriter.WriteCityJsonSeq(cityJsondocuments, "output.city.jsonl");

Convert CityJSONDocument to NetTopologySuite:

var features = cityjsonDocument.ToFeatures(vertices, transform);

Converting CityJSON object to NetTopologySuite:

var feature = cityObject.ToFeature(vertices, transform);

Tools

• cj2glb: from CityJSON to GLB

Created glTF file contains 3D Tiles extensions EXT_Mesh_features + EXT_Structural_Metadata for storing attribute information. Also a tileset.json file is created with a reference to the glTF. When there is no projection info in the input file, some default projection is used.

Sample usage cj2glb:

• Download CityGML from https://www.citygmlwiki.org/index.php?title=FZK_Haus,_CityGML_3.0,_LoD2,_No_Storeys,_Boundary_Surfaces and unzip

• Convert to CityJSON using citygml4j/citygml-tools:

$ docker run -v /data/fzkhaus:/data citygml4j/citygml-tools:2.4.0 to-cityjson /data/01-FZK-Haus-LoD2-Tex-no-Storey-CG30-V01.gml 

Result: 01-FZK-Haus-LoD2-Tex-no-Storey-CG30-V01.json

• Convert to GLB using cj2glb:

cj2glb 01-FZK-Haus-LoD2-Tex-no-Storey-CG30-V01.json fzk_haus.glb

Result: fzk_haus.glb

Supports

• Geometry type support: Solid, CompositeSurface, MultiSurface, MultiSolid, CompositeSolid;

• Interior rings;

• Appearance support: Textures, Vertices-Texture;

• CityObject - Address

• Metadata support (EXT_Mesh_Features + EXT+Structural_Metadata)

• Creates tileset.json for use in 3D Tiles

• Reading and writing CityJSON files

Limitations

• No support for extensions, materials;

History

2026-01-05: release 2.5 - from .NET 6.0 to .NET Standard 2.0

2025-11-12: release 2.4 - Adding writing support

2025-06-19: release 2.3 - Adding attributes support

2025-05-06: release 2.2 - Adding textures support

2025-01-15: release 2.1 - Reading CityJSON 2.0 Seq files

2024-12-06: release 2.0 - Refactoring - Reading geometries

2024-12-04: release 1.1 - to .NET 8.0

2022-11-22: from CityJSON 1.0.1 to CityJSON 1.1.2

2022-11-22: to .NET 6

2020-07-27: original coding