IFC GUID import/export

hi Jon,

Jon Summers said:

When OBD exports to IFC, does it generate a GUID for each graphic element or component?

Yes, it does. With CONNECT Edition Update 2, it was enhanced so that the GUID remains the same every time elements are exported.

https://docs.bentley.com/LiveContent/web/Designer%20Help-v1/en/GUID-F8EF26D2-B5CC-4529-903C-E3E0541D3FAD.html

Jon Summers said:

When OBC imports from IFC, does it attach the IFC GUID to the equivalent DGN element or component?

When imported, IFC GUID value is attached  as the GlobalId in the resepctive IFC properties.

Best Regards,

RJ.

It’s positive to see that the updated IFC exporter stabilises the IFC GUID allocation. The implication of the update suggests that the IFC GUID is stored in the DGN file in order to allow its persistence on subsequent export. If that is the case we have what we need to round-trip the IFC GUID between third-party apps. and OBD.  Can you confirm that to be the situation?

Jon,

My apologies, may I please request additional information on your thoughts about

Jon Summers said:

to round-trip the IFC GUID between third-party apps. and OBD.

Best Regards,

Raguram.

Jon,

I was discussing your query with our team.

I was told, the platform open reference ignores GUIDs and we have no official import for building elements (Design Transfer View).

Please accept my apologies for my incorrect answer regarding the import, and  if my reply caused any inconvenience / trouble.

Best Regards,

RJ.

Raguram Jayaram said:

may I please request additional information

Sure!

1. A third-party creates an IFC.  Objects in that IFC file are tagged with the IFC GUID.
   1. Someone imports that IFC into OBD.
   2. IFC objects are translated to DGN elements. 
   3. Each element is tagged with IFC property GlobalId.
2. The DGN file is exported to a new IFC file. 
   1. What happens to the IFC GlobalId properties? 
   2. Can a consumer correlate objects in the original IFC with those in the exported IFC by comparing their IFC GUIDs?

That's what I mean by round trip. 

Jon,

Thank you for explaining.

Jon Summers said:

The DGN file is exported to a new IFC file. 

1. What happens to the IFC GlobalId properties? 

When exported, the existing GlobalId of the dgn element is ignored and new IFCGUIDs are created in my test case.

Jon Summers said:

Can a consumer correlate objects in the original IFC with those in the exported IFC by comparing their IFC GUIDs

Because the IFCGUIDs are different, correlating objects based on IFCGUIDs would not be accurate.

Best Regards,

RJ.

Jon,

Thank you for explaining.

Jon Summers said:

The DGN file is exported to a new IFC file. 

1. What happens to the IFC GlobalId properties? 

When exported, the existing GlobalId of the dgn element is ignored and new IFCGUIDs are created in my test case.

Jon Summers said:

Can a consumer correlate objects in the original IFC with those in the exported IFC by comparing their IFC GUIDs

Because the IFCGUIDs are different, correlating objects based on IFCGUIDs would not be accurate.

Best Regards,

RJ.