How much can you change an element and still be the same

[Matthew Johnson]

We are working on a project with engineers in Revit and importing their data in via IFC. When the model data comes in the geometry is in the right locations/storeys and has Building Materials that match the source. Unfortunately the representations don't always match what we'd like to display in our documents.

For example some columns have the background cut fill pen overridden, slabs show on either storeys above or below that we don't really want to see, pen colours don't match our standard, all columns are in one layer (not separated by steel/concrete as our standard)...

What we would like to do is be able to modify some of the element attributes to make the elements appear the way we'd like them to but still maintain the connection to the original IFC data so that we can later run a "Detect IFC Model Changes" and update the geometry/location/IFC data of elements without having to re-assign pens, colours, layers again.

If the GUID remains unchanged are there properties that can be modified in ArchiCAD without breaking the link to the original engineer's IFC data source?

Can these properties survive an update of the IFC data without reverting back to their original display settings?

[Laszlo Nagy]

Unfortunately I will not be able to answer your question because I don't have enough experience with this scenario.
But if I understand correctly you are importing IFC from Revit directly into your project file and use those elements. As far as I know this is not something Graphisoft recommends as a workflow. They recommend a reference model approach, where you only use the model imported from Revit as a reference, but model in your own project file.

[Matthew Johnson]

Thank you for taking the time to reply Laszlo. Generally we use the workflows that Graphisoft suggest, but as anyone who knows me will attest I often try to push the workflows to do just that little bit more.

What I'm trying to get around is an issue with the import of IFC into our project that sets the floor plan display settings for many of the elements to show on irrelevant storeys. Footing elements are showing on the 2nd floor, 1st floor columns are showing on the foundation storey, etc.

What I want to experiment with is setting all imported elements to show on home storey only and then not having to re-do this every time we update the reference model.

I'm curious if anyone else is trying this or if the development team has any insight into how this might work

[Laszlo Nagy]

If elements get placed and shown on Stories where they are not supposed to go by any logic, then I think this could be a bug, in which case it deserves the attention of the developers. The question is always whether it is a bug in Revit export or ArchiCAD import or something that is just the limitation of IFC. But that developers will be most qualified to decide that so I would send these files as a package to your local reseller, who will forward it to Graphisoft to look at and find out if they can do anything about it on their side (or maybe let the Revit guys know so they can fix it - it has happened before )