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Autodesk / revit-ifc

IFC for Revit and Navisworks (2019+)
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Option to prevent export of IfcAdvancedBrep #480

Open jmirtsch opened 2 years ago

jmirtsch commented 2 years ago

I'd like to seek opinions on an export option for IFC4 Design Transfer View to prevent IfcAdvancedBreps. Not many implementations support this concept well. From my testing, Revit will often not try and detect extrusions prior, so IFC files can be larger than they need to be.

IFC4 Reference view does not include many semantic concepts (eg material layers) that are needed for exchange workflows, hence many projects persisting with IFC2x3 Coordination model view. If an export option to prevent advanced breps was enabled, it would help facilitate more advanced workflows using IFC4.

AngelVelezSosa commented 2 years ago

If advanced BReps are a problem (and I can understand how they are/would be), it seems like better solutions would be:

  1. Implement a "fallback" similar to that being used in IFC4.3, and most importantly
  2. Create an MVD that would support this, given that DTV doesn't actually exist.
Moult commented 2 years ago

The two big players that don't support IfcAdvancedBreps are Solibri and Trimble.

I think the bigger issue than IfcAdvancedBReps being unsupported by those two is that Revit seems to unnecessarily use IfcAdvancedBReps for things that could easily be an extrusion or polygonal face set instead. Advanced BReps should only be used for... well, advanced things.