@cityjson/cjconv

Convert 3D city models between CityJSON, CityJSONSeq, FlatCityBuf, CityParquet packages and OBJ, keeping only the levels of detail and attributes you need. A command line (cjconv) and a Node library, powered by the cityjson DuckDB extension through @duckdb/node-api. A browser version lives at https://cityjson.github.io/convert/.

Experimental: verify results before relying on them.

Command line

npm install -g @cityjson/cjconv

cjconv delft.city.jsonl delft.fcb                          # format from the output name
cjconv delft.city.jsonl delft.city.json --lod 2.2 --attributes status
cjconv delft.city.jsonl delft_pkg/                         # CityParquet package (a directory)
cjconv delft_pkg delft.city.jsonl
cjconv https://cityjson.open3d.city/cityjsonseq/delft.city.jsonl delft.fcb
cjconv info delft.city.jsonl                               # format, CRS, LoDs, attributes
cjconv tile-1.city.jsonl tile-2.city.jsonl delft.fcb       # combine tiles into one output
cjconv --help

On first use the cityjson extension is installed from DuckDB's community repository (network access needed once; it is cached in ~/.duckdb). --extension <path> loads a local build instead.

OBJ needs a cityjson build newer than the community one, which predates OBJ support: pass --extension. An OBJ states no LoD or CRS, so give them: cjconv cube.obj cube.city.jsonl --obj-lod 2.2 --crs EPSG:7415.

Several inputs are pieces of one dataset, combined into the one output (the last argument). An id in more than one input, a column holding different kinds of values between inputs, or inputs in different CRSs are refused rather than guessed at.

Library

import { convertFile, inspectFile } from "@cityjson/cjconv";

const info = await inspectFile("delft.city.jsonl");
console.log(info.schema.lods, info.crs);

const { files } = await convertFile({
  input: "delft.city.jsonl",
  output: "delft.fcb",
  lods: ["2.2"],
  attributes: ["status"],
});

// Several tiles into one file
await convertFile({ input: ["tile-1.city.jsonl", "tile-2.city.jsonl"], output: "delft.fcb" });

For several conversions, create one engine with createNodeEngine() and pass it as engine to avoid loading the extension each time. The engine-agnostic logic underneath is @cityjson/cjconv-core.

MIT licensed.