Remove hardwired geographical coordinates system code

[EricBoix]

Within IfcTiler/ifcObjectGeom.py code like

transformer = Transformer.from_crs("EPSG:27562", "EPSG:3946")

hard-wires

• the knowledge projection system of the input data (we could have another system for the input)
• the projection system of the resulting 3dTiles output (the user might like to specify another projection system)

Such a rewriting/conversion should be within the Tiler but outside of it. Let the Tiler produce a 3dTiles using the projection system of it's input. Then write a 3dTiles converter utility (CLI) that converts the projection system. This would separate the concerns.

[clementcolin]

In order to write a clean 3DTiles converter utility, there is some work to be done in py3dtiles first. Indeed, there is currently no 3DTiles (tileset.json) reader :

• only tiles reader exist here and used here
• the current tileset class only allows to write a tileset but not to read from one

Once we are able to read a tileset, we should then be able to modify it, i.e, in this case, change the projection system used.

A quick but dirty solution would be a script that load the tileset.json and look for transformation and extent matrices in order to modify them.

[EricBoix]

Concerning the 3dtiles deserialization process refer to this issue.

[LorenzoMarnat]

This PR introduce crs_in and crs_out flags. The crs_in flag allows to specify the input CRS (default is EPSG:3946). The crs_out flag projects the geometries in another CRS (default output CRS is EPSG:3946). Those flags can be used by any tiler inheriting from Tiler class.

Example with the IfcTiler

ifc-tiler path/to/ifc --crs_in EPSG:4171 --crs_out EPSG:3946