When i create an IFC export of my Revit model, i 'loose' material assignment's to other software, but not when i re-import the IFC into Revit.
It seems that Revit uses the IfcSurfaceStyle for Material's in stead of the IfcMaterial property..
Anybody know why, and even better.. a way to fix the IFC?
Actually, Revit uses both IfcSurfaceStyle AND IfcMaterial. However, in the past, Revit didn't export materials as universally as it does now, so if you get the most current Open Source DLLs, it may be that the problem has been solved.
If not, if they please provide more detail.