Modify or delete built-in IFC Properties - IFC export

[AlexV]

I've encountered an issue when exporting an ifc:  there seems to be some properties that Archicad controls itself and are not accessible via property mapping. I cleared out all Psets from the Property mapping, and all the boxes from data conversion but there are still a lot of ifc data that Archicad saves and that I can't seem to be able to control.

Is there a way to clear all that or some of those tabs from the ifc export? and save only some selected properties? or at least change how that data is being extracted and named in ifc exporting?

While I understand most of them are useful, in my case the BIM manager requires specific metadata exported, and while I can create a custom pset that mapps ifc properties from specific Archicad properties according to the requirements, I can't delete or change the name of the the properties in those tabs.

Usually it's not a problem but in this case there are conflict between the names bc several properties are saved with the same name( one mapped by me, one mapped by Archicad) that will show different information and my ifc gets rejected - they use some sort of automated script that searches for specific text for ifc properties and does not allow duplicates and ofc does not allow inconsistency.

There are multiple issues I've received but for example under the Identification tab there is the "Type" property that shows either the composite name, or the building material name or the custom profile name for walls, slabs and roofs or " railing type" for railing or the library part name for windows and doors etc.

[Nathan Hildebrandt]

Firstly the information you have going out is to comply with the base information that needs to go out in an IFC. There is a lot of effort that you need to go to, to get a clean (data) export through mapping. It starts with having a strict attributes naming approach and you may also need to use unique ID’s for every element. To learn the approach to doing this right isn’t something you can learn or teach in a few responses in this forum. It is a custom training exercise that you would need to go through, sorry to say. 

[AlexV]

@Nathan Hildebrandt 

I think I understand what you mean, and I already know some of the issues can be fixed by good information practices- for example correct naming all the building materials & profiles, but some can't, bc. for the material example - if the client has a specific demand that the ifc-property needs to be called "Materials" instead of "Material" -like AC saves by default , I can't change that from IFC export. So it's easier to create a separate ifc property called" Materials" and export that. Which is fine by the client.

- the problem comes when the property is already saved with the same name by AC & shows a completely different thing than the client wants- then if I create a custom property and bc. I can't delete or modify the one AC saves by default- it will just be 2 ifc properties with the same name & only one showing the correct info. that's a no-no.

The way I do it now is using SimpleBIM, it has a trimming function that allows me to delete ifc properties but I am looking into maybe fixing it from inside AC, rather than using another software.

[Nathan Hildebrandt · Accepted solution]

Material is a challenging example as it is something we can't map or override. Maybe that is something to add to the wishlist. I would also ask the client why they want the property name to not align with the standard and be slightly different. If the property was named more differently then that would be understandable. 

Sadly, yes simplebim is one of the only tools available that can edit it.

[stefan · Accepted solution]

If it's just renaming and it's predictable where it ends up in the IFC file, you can use a post-export script to automatically rename the problematic property set. Any programming language can do this. Or if you are knowledgable with Python and understand the IFC scheme, use the ifcopenshell library to fix the IFC file in one go.

That said, be aware that the tab that Solibri shows is its own interpretation, based on the materials in the model which are referenced by elements. There is no property set called "Material" in the IFC file.

[AlexV]

Thank you, this is interesting... although I wish GS would make it easier to do this from within AC, I will look into it.

Another thing that strikes me now is your last paragraph... I was living under the impression that the property grouping in Solibri is set in stone, maybe based on a standard (like the ifc 2x3 scheme or smth). That changes the approach a bit.

[stefan]

Yes, Solibri "friendlyfies" some of the IFC information. All "tabs" up to Hyperlinks in the INFO panel are NOT property sets, but is Solibri collecting information into a decent overview:

• Identification - bits and pieces from different places (attributes, representation, file info...)
• Location - bits and pieces from LocalPlacement and containment relationships + calculated info from the Bounding Box
• Quantities - NOT the BaseQuantities, but Solibri interpreting the geometric representation (!) This info is derived by Solibri but cannot be found as-such in the model
• Material - names of references materials and thickness if a MaterialLayerSet is referenced. No material properties are visible, that I'm aware of
• Profile - name of the profile as referenced inside the geometric representation
• Relations - various objectified relations (via the inverse attributes in the entity/class)
• Classification - combination of Classification References from the IFC file and Solibri-generated classifications from the loaded classification rules (= interpretation)
• Hyperlinks - Solibri-provided URLs (if I'm not mistaken)

Moreover, there is no "ceiling" class in IFC. What Solibri shows as ceiling is in fact an IfcCovering with PredefinedType CEILING.

And there is no instantiatable "object" class in IFC. What Solibri shows as "object" is an IfcBuildingElementProxy.

[stefan]

Beware that almost all of the "interpreted" information from Solibri can be controlled from within Archicad, apart from a few of the hard-coded translations to IFC. E.g., classifications is a real strength Archicad has over Revit, in the way you can control and map properties to IFC.