topic Re: Revit User Import Capability - IFC4 in Collaboration with other software

Revit User Import Capability - IFC4

Aaron Bourgoin — Wed, 14 Dec 2022 21:30:25 GMT

What does a Revit user do to import an IFC 4 file. Autodesk and Revit sites Bothe say that Revit can import an IFC4 file, but can only import IFC 2x3.

If we export IFC4 files, can they convert these in a different application for use in their projects? If yes, what?

Re: Revit User Import Capability - IFC4

MF BIM — Thu, 15 Dec 2022 09:29:38 GMT

If I recall right, IFC4 imports are possible starting from Revit 2022 so they may just need to use a later version.

Re: Revit User Import Capability - IFC4

Aaron Bourgoin — Thu, 15 Dec 2022 15:07:25 GMT

If have no control over which version of Revit my teammates are using. That's why I'm asking if there are applications that can read IFC 4 and save back to 2x3?

Re: Revit User Import Capability - IFC4

Jim Allen — Fri, 16 Dec 2022 12:22:37 GMT

My office uses IFC model transfer with Revit for every project, and we use IFC 2x3.

I have been told by GS support that IFC 4 is not particularly well (consistently) supported by Revit yet, and our experience backs this up.

Even IFC 2x3 has its issues with the ability of Revit to recognise walls, windows, doors (including 2D display of swings) etc, and its ability to insert fittings onto the imported structure.

We had to make our own export filters specifically for Revit MEP to get it to work properly.

Almost every thing works as it ought - but there is a problem with anything using SEOs - cut geometry is ignored.

To get SEO trimmed geometry to display in Revit you need to use boundary representation mode, which breaks other functional requirements.

So if you want genuine interoperability between GS and Revit between disciplines using different software, you can do it, but from our experiments, there is a single limitation with SEOs.

IFC4 is not the optimal solution - we spent days experimenting, and didn't get it to work properly in Revit

Re: Revit User Import Capability - IFC4

Laszlo Nagy — Tue, 20 Dec 2022 04:13:20 GMT

According to buildingSMART:

https://technical.buildingsmart.org/services/certification/ifc-certification-participants/

Revit is certified for IFC4 Architectural Reference Exchange Import and Export.

As far as I know, the keyword here is "Reference" because there are other types of IFC4 exchanges as well.

In Archicad, you would have to use the "IFC4 Reference View-based Export" IFC Translator for this (it uses Precise BREP geometry conversion). The other default IFC4 Translator in Archicad is "IFC4 Design Transfer View-based Export" but that one uses extruded geometry export.

You could also use the IFC Add-On for Revit that improves IFC exchange with Archicad.

It would be good to know the exact issue (e.g. certain element types are not converted properly) so we can provide better answers.

Re: Revit User Import Capability - IFC4

Jim Allen — Tue, 20 Dec 2022 17:56:07 GMT

In my office nothing we tried with IFC4 worked properly with Revit.

Despite what Autodesk or its certification say, my colleagues and I couldn't get it to work, even with the Graphisoft Revit IFC plugin and assistance from GS UK TEch support - who are stellar.

IFC2x3 was difficult enough - we must have tried all the options, and almost every time we had some issue or other. Sometimes 2d door swings were missing, sometimes walls weren't able to receive Revit electrical fittings, sometimes SEOs won't display, sometimes windows and doors had other display issues.

Unless people have tried it personally and achieved success with models with any degree of complexity (for example complex profile walls, SEOs etc) and can share exactly what their results have been so we know what to do to get IFC 4 transfer to work - quoting standards is just unhelpful.

Re: Revit User Import Capability - IFC4

Laszlo Nagy — Sun, 25 Dec 2022 14:39:57 GMT

Hi Jim,

Did you guy report these issues? I am sure if you report it to Graphisoft, they will do whatever they can on their side for the exchange to work with IFC 4.

Re: Revit User Import Capability - IFC4

Jim Allen — Wed, 04 Jan 2023 14:55:13 GMT

Hi Laszlo,

The approach we are using is one that was recommended by GS support - as I mentioned above.

I was told quite specifically that IFC4 exchange with Revit just doesn't work very well.

I don't know if there is some internal GS tech support knowledgebase that has tested exactly what works and doesn't with Revit IFC export, but it's not enough just to import a file into Revit, you need to be able to do something with it, and if no-one has actually tested placing Revit electrical fittings on imported IFC walls, you won't know if it actually works properly.

Just seeing the geometry in Revit which looks kind of right (2D door swing display issue aside) isn't enough. I was able to sit in the same room as my Revit using colleague while he was trying add electical fittings to see what was working.

What we do know, is that using certain IFC export options we are able to get Revit to treat imported IFC walls pretty much the same as native Revit ones, which is great, and is the main criterion.

However, from our tests (this does take several hours) we were only able to do it with IFC 2x3 and without boundary representation, so no SEO cuts.

It's entirely possible we were missing something, but eif so I would be surprised, because we were quite methodical in our testing.

Re: Revit User Import Capability - IFC4

Karoly Horvath — Wed, 15 Nov 2023 09:19:30 GMT

This is interesting.
I have been using IFC 4.0 for over a year.
We specifically changed the format to improve speed.
For example:
Export IFC 2x3 from Archicad 25 takes 35min.
Export same model to IFC 4.0: 3 min
Revit import:
The trick is: In Revit you should not try to open the IFC 4.0 model. You should Insert it instead.
The model is inserted in 20 minutes. While Revit inserts the IFC 4.0 model, it generates a rvt file in the folder where you had the IFC file.
The generated rvt file is perfectly usable for background and for clash detection.

Re: Revit User Import Capability - IFC4

Laszlo Nagy — Wed, 15 Nov 2023 10:41:29 GMT

Karoly,

Do you mean to "Link an IFC" file in Revit? I think that is what the command is called.

Re: Revit User Import Capability - IFC4

Karoly Horvath — Wed, 15 Nov 2023 13:38:04 GMT

Yep.

Simple 😉

Re: Revit User Import Capability - IFC4

Jim Allen — Wed, 15 Nov 2023 17:50:40 GMT

Since the original post was made, quite a lot of time has elapsed, and my office are now using AC27 instead of AC25.

Revit has also been updated. It may be that IFC4 works fine with AC27 and the latest version of Revit. If so, it's good news.

I've had a lot of success with importing Revit structural drawings into AC27. There were a few wrinkles, but these might have been user error in the Revit model.

Depends what you are doing though. Inserting an IFC file into Revit may indeed work fine insofar as the geometry displays as it ought.

What should happen is that doors and windows display properly in 2D and 3D and that imported IFC walls should be able to host Revit family components like building services equipment. Although the IFC imported and displayed just fine in 3D, when we tested it, it didn't in 2D and had functional issues.

I'm hoping it's fixed now, but I haven't checked in AC27.

Re: Revit User Import Capability - IFC4

Karoly Horvath — Wed, 15 Nov 2023 23:28:08 GMT

I have only worked with Archicad 25 and Revit 2022, so don't know how the current versions behave.

Also, I did not even dare to expect anything more than correct geometry out of IFC 4.0 conversion.

To make things really usable, I should be able to receive the Structural elements from Revit as native elenents. I mean: slabs should be slabs, walls = walls and column are columns when I import them into Archicad. No objects ols. (And of course vice versa)

I strongly support the idea of not modeling things twice. Struct eng modelled the structure, I import and don't model again. That would not only save time, but reduce errors a lot!

Same goes for services: mec and electronic can place the on ceiling services (second fix), so why should I repete it as an a? I should just review and maybe move stuff, but not model it all again...

One day this will work.

It may need a nit of AI learning algorithm to convert elements to native elements properly.

Re: Revit User Import Capability - IFC4

Jim Allen — Thu, 16 Nov 2023 11:49:01 GMT

In terms of structure at least, imported IFC structure exported from the structural engineer's Revit model works really well in AC27 - in fact pretty much as you describe.

Haven't checked to see whether the building services issues have been fixed though.

Re: Revit User Import Capability - IFC4

Karoly Horvath — Thu, 16 Nov 2023 13:17:49 GMT

I just have to check that out. If you are right I will have a celebration party!