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Modules

The module system in DTCV is based on JS/TS modules in relation to the package system of NPM and a monorepo setup.

The idea is to create reusable modules in the packages directory for the applications with many of the common library functions needed for digital twin cities.

This initially included several "not invented here" efforts to learn about the formats and how the geometry and geospatial data should be processed.

At a later stage most of the modules were replaced by existing NPM packages, especially from the OpenVisualisation ecosystem of powerful libraries that emerged in the last couple of years.

Modules​

In the packages directory it is possible to add resuable modules and import them into different applications.

Examples of modules developed in DTCV are:

├── citygml/ # CityGML format support
├── cityjson/ # CityJSON format support
├── citymodel/ # City model abstractions
├── convert/ # Common conversion functions
├── entity/ # Entity abstraction definitions
├── geojson/ # GeoJSON format support
├── indicators/ # Common indicators for data analysis
├── osm/ # OpenStreetMap integration
├── projection/ # Map projections
├── vectortiles/ # Vector tile creation
└── viewer/ # Common viewer wrapper

Here is a link to the modules on github.

Valuable module resources​

There are some resources that are useful when developing applications for digital twin cities:

  • deck.gl - Core visualization framework for large-scale geospatial data with WebGL-powered layers
  • @math.gl/core - Basic math classes for geospatial and 3D use cases
  • @math.gl/geospatial - Ellipsoidal math for WGS84 coordinates
  • @math.gl/web-mercator - 3D Web Mercator projections
  • @math.gl/polygon - Polygon math and geospatial cutting
  • @math.gl/sun - Solar position calculations
  • @math.gl/dggs-geohash - GeoHash token operations
  • @math.gl/dggs-quadkey - QuadKey token operations
  • @math.gl/dggs-s2 - S2 token operations
  • @loaders.gl/csv - CSV streaming parser
  • @loaders.gl/json - JSON and GeoJSON parsing
  • @loaders.gl/kml - KML file parser
  • @loaders.gl/wkt - WKT/WKB format parser
  • @loaders.gl/mvt - Mapbox Vector Tiles loader
  • @loaders.gl/las - LAS/LAZ point cloud parser
  • @loaders.gl/obj - OBJ 3D model loader
  • @loaders.gl/terrain - Terrain data loader
  • @loaders.gl/3d-tiles - 3D Tiles format loader
  • @loaders.gl/i3s - I3S format loader

You can use the available react abstraction on top of MaplibreGL (or actually a Mapbox wrapper)

  • react-map-gl - React components for MaplibreGLintegration

Also read up on the amazing Luma library that we started to build DTCV on top of:

  • luma.gl - Low-level WebGL2 library for custom visualizations