Other CityGML Themes

[alavenant]

Hello,

I'm using the citygml-tiler tool.

Have you plan to deal with other CityGML themes : transport, vegetation, cityfurniture, ...

Thanks,

[LorenzoMarnat]

Hello

The CityTiler currently supports 4 thematic models: buildings, waterbodies, relief and bridges.

It would be really interesting to support other themes. The development time to support another theme depends on the geometry used to represent a CityObject:

• If the geometry is MultiSurface/MultiSolid/Solid, the code to parse it already exists in Py3DTilers and we just have to adapt the Postgis requests to support new themes. Example: Bridge support PR.
• Other geometries would require more work to be supported, such as supporting I3DM 3D Tiles or new triangulations methods

I'll see how this work could be integrated in the roadmap of Py3DTilers. I think vegetation would be the more interesting new theme to support, but also the hardest one.

About transport

Supporting Transportation Model should be similar to relief since the geometry is MultiSurface. This can be easily triangulated and transformed into B3DM 3D Tiles.

About vegetation

• Supporting PlantCover of Vegetation Model shouldn't be really difficult since the geometry is either MultiSurface or MultiSolid. Those geometries can be easily triangulated and transformed into B3DM 3D Tiles.
• Supporting SolitaryVegetationObject of Vegetation Model can be more difficult if the geometry is implicit (meaning the objects share the same geometry but have different positions). Supporting implicit geometry would require Py3DTiles/Py3DTilers to support I3DM 3D Tiles. Another solution would be to create one geometry per SolitaryVegetationObject instance (and then use B3DM to represent those objects), but this solution may cause optimisation issues when visualizing the 3D Tiles.

About city furniture

As well as vegetation, CityFurniture Model can use an implicit geometry, which requires to either supports I3DM or create an unique geometry per object.