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How to link files (external information) like PDF documents to an IFC file?

Hi everyone,

I need help with a requirement of a system we are building and I hope someone could bring some light to the matter.

To be short, we are enriching existing IFC files with some structured data we have in our database.

One requirement implies that we enrich the IfcProject entity of the IFC model with links to different documents (PDFs, images, MS word…) located at our servers and uniquely identified through a URI.

We have been looking at different Ifc entities as you can see in the screenshot bellow (IfcRelAssociatesDocument, IfcDocumentExternalReference…).

So the question is if that’s the correct way to link information of external resources to some entity of the IFC? Did we chose the right entities?

If anyone had experience with enriching IFC files and had faced similar needs, it would be much appreciated to hear your thoughts.

Thank you.

I come to the same conclusion as you from the spec. However, I’ve never seen it applied in practice.

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The correct way to associate documents to the IfcProject as general external documents applying to the IFC data set is defined here:

However, as @Moult mentions, it is not well supported by current tools. A related question - where do the referenced documents live? It could either be at any URL, or those can be included in an *.ifcZIP file (but there is still the need to defined a standard directory structure of such *.ifcZIP files).

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Thank you for the clarification, then IfcRelAssociatesDocument is the way to go, and we are going to use URLs as you mentioned.

yes, and you can also attach document references directly to model element, e.g. a ground floor plan to IfcBuildingStorey or an maintenance instruction manual to IfcPump.

See: https://standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/link/document-association.htm

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