How to identify the orientation of façade elements in IFC?

Developers IFC2x3
1

Hi everyone,
I am trying to extract with a simple Python script the façade elements (I am focusing on Walls and Windows only) according to their orientation from an ifc2x3.
I am struggling in finding information on how to identify the orientation of an element. My idea woud be to first identify External IfcWalls (i.e. IfcWindows) and then to access another attribute or property them provides the orientation.
It seems to me that the TrueNorth associated to a project is the entrypoint to my problem.
Thanks!

2

Hi Pierre (assuming it’s you),

For exterior elements, you might want to have a look at GitHub - opensourceBIM/voxelization_toolkit: Voxelization Toolkit for (IFC) Building Models it comes with a predefined script to extract elements voxelization_toolkit/__init__.py at master · opensourceBIM/voxelization_toolkit · GitHub

For orientation it’s easiest to look at the IfcWall Axis representation that gives you the direction of the wall in 2D.

I’m not sure how often TrueNorth is correctly specified these days. I guess it’s superseded mostly by IfcMapConversion in IFC4. But in practice I guess on the average model these days neither are specified reliably.