# Lyon with LODs

In this tilset, buildings have different LoD (Levels of detail): one is LoD1 (simplification of models) and the other is LoA (Level of Abstraction) where different buildings are abstracted by one geometry.

## How to create those tilesets

The tileset was created with [Py3DTilers](https://github.com/VCityTeam/py3dtilers), an open source toolkit to create 3D Tiles out of various geometrical formats (OBJ, GeoJSON, IFC or CityGML), using the [CityTiler](https://github.com/VCityTeam/py3dtilers/tree/master/py3dtilers/CityTiler).

Buildings are CityGML models from open data and can be found online: [Lyon 1 to Lyon 9 CityGML (year 2018)](https://data.grandlyon.com/jeux-de-donnees/maquettes-3d-texturees-2018-communes-metropole-lyon/donnees) of Data Grand Lyon.

Roads are from open data and can be found online: 'TRONCON_DE_ROUTE' of [BD TOPO DÉPARTEMENT SHAPEFILE - RHÔNE](https://geoservices.ign.fr/telechargement) of IGN. Data was converted from Shapefile to GeoJSON with [QGIS](https://www.qgis.org/en/site/).

The polygons used to create the LoA of buildings were computed with QGIS using the 'Vector geometry/Polygonize' operation on the roads data described above. The file containing those polygons is available [online](https://github.com/VCityTeam/UD-Sample-data/blob/master/GeoJSON/polygons_loa_lyon.geojson).

To install and use Py3DTilers, see online documentation: [installation](https://github.com/VCityTeam/py3dtilers?tab=readme-ov-file#installation-from-sources) & [usage](https://github.com/VCityTeam/py3dtilers?tab=readme-ov-file#usage).

The command used to created the tileset is:

```bash
citygml-tiler -i py3dtilers/CityTiler/CityTilerDBConfig.yml --type building --loa <path>/polygons_loa_lyon.geojson --lod1 -o Lyon_2018_LOD_Buildings_TileSet
```