@jwouellette I have a similar experience as @bernd and @Hans_Lammerts. I also receive IFCs on a weekly basis with these issues. Allow me to give one example. Here is the source scene, exported from BlenderBIM - two IfcWall objects - one red, one green. The red is assigned the surface colour directly to the object’s representation via styled item, and the green is assigned via IfcMaterial with IfcMaterialDefinitionRepresentation.
Solibri opens and shows both colours without any issue - great job, Solibri!
In Revit, it also works as shown below…
… but, it only works in Revit with a few considerations. And it is these considerations which, I believe, result in a poor user experience.
Here is one scenario of the exact same file except that the geometry is an IfcFacetedBrep, instead of an IfcExtrudedAreaSolid. You can see that the green colour no longer shows. This is the most common reason, I find, for colours not showing. Logically, shape representation should not affect colour display. In this case, I believe it affects it because of the way Revit tries to parse an IfcWall, but since Revit is a black box, I cannot say for sure.
The additional quirk is that the red cube actually creates a new material in Revit called “red”, even though there is no such IfcMaterial('red' ... in the source IFC file. This misleads people into thinking that materials are being imported or exported, where in fact, Revit is actually reading the Name attribute of the IfcSurfaceStyle entity, and seems to completely ignore the Name attribute of the IfcMaterial entity, which, you’d hope, is where it actually picks up materials from.
Given that Revit is certified, I find it strange that these issues exist.
A third quirk is that the IfcStyledItem has this little deprecation notice:
NOTE Only the select item IfcPresentationStyle shall be used from IFC4 onwards, the IfcPresentationStyleAssignment has been deprecated.
This means that for IFC4 files (yes, I know, in theory Revit is not yet certified for IFC4 import), since Revit only supports IfcPresentationStyleAssignment, colours will not show up. Because Revit isn’t certified for this, we can’t exactly fault them, but it certainly causes users problems nonetheless. Even worse, it gives people a bad impression of IFC as a file format they can’t trust.
This short case study into Revit (2019 - maybe fixed in 2020?) is just one example you can see that XBim displays the file like this - it ignores the green material, but applies the red object style. There are quite a few other vendors that also have this issue.
