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Collaborate forum

IFC structural vs architectural model discrepancy checking

Paul King
Expert
HI - I am looking for an efficient way to do essentially the opposite of collision detection.

As the architectural model evolves, positions of hundreds of elements move around.
An engineer who sends you his IFC for coordination purposes may well be basing it on an earlier version of your model, imported into Revit, and may not have (usually hasn't) kept up with your issued changes.

I have in the past done things like making the engineers IFC red, and the architectural model semi translucent to visually highlight issues with alignment or extent of elements, or breaches of the geometric architectural envelope allocated for structure, painfully capturing screenshots of same and manually marking up plans showing each and every discrepancy location - but this takes an awful lot of time, and given that it seldom completely successful in eliciting the engineer's update anyway, it is typically a deeply unproductive use of time.

I can't get engineers to search for discrepancies themselves - they seem to think this is the architect's job.

How can I automate this search and report process, and get ArchiCAD to identify the structural elements or even just architectural elements that the engineer is reflecting that are out of sync with the current architectural geometry?
PAUL KING
https://www.prime.net.nz
ArchiCAD 8-25
Octane Render Plugin for ArchiCAD
Twinmotion 2022
Windoze 11
Intel Core i9 10900K
Nvidia Gforce RTX 3080
32 Gb DDR3
2x4K monitor extended desktop
5 REPLIES 5

Barry Kelly
Moderator
Have you looked at Model Compare in version 24?

https://helpcenter.graphisoft.com/user-guide-chapter/85629/


Barry.

One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10

Paul King
Expert
Hi Barry - that is broadly aligned with my goal, though the model I need to compare with is generally generated in Revit before being imported via ifc into ArchiCAD, which my brief reading suggests would count it out for discrepancy checking , on the basis that there are no element IDs in common with the original architectural model?

What do people usually do in this situation? What is best practice workflow for reporting on discrepancies between models from different platforms?
PAUL KING
https://www.prime.net.nz
ArchiCAD 8-25
Octane Render Plugin for ArchiCAD
Twinmotion 2022
Windoze 11
Intel Core i9 10900K
Nvidia Gforce RTX 3080
32 Gb DDR3
2x4K monitor extended desktop

Karl Griffith
Booster
Not sure if this will do it, but I have used 'Detect IFC Model Changes' for similar purposes (File>Interoperability>IFC>Detect IFC Model Changes). Works pretty well, but the engineer I was working with was modeling rebar and that would result in the identification of hundreds of changes for minor wall changes. But I could still chase down model changes. In this case, I usually wasn't even told of the changes (I was a consultant to the engineer).
ArchiCAD 22

Win 10

Paul King
Expert
Karl wrote:
Not sure if this will do it, but I have used 'Detect IFC Model Changes' for similar purposes (File>Interoperability>IFC>Detect IFC Model Changes). Works pretty well, but the engineer I was working with was modeling rebar and that would result in the identification of hundreds of changes for minor wall changes. But I could still chase down model changes. In this case, I usually wasn't even told of the changes (I was a consultant to the engineer).
Thanks Karl - another good thought. Will this compare ifc models produced by completely different platforms though? - I am assuming it is for comparing two versions of same model - so there will be some sort of continuity of object ids?
PAUL KING
https://www.prime.net.nz
ArchiCAD 8-25
Octane Render Plugin for ArchiCAD
Twinmotion 2022
Windoze 11
Intel Core i9 10900K
Nvidia Gforce RTX 3080
32 Gb DDR3
2x4K monitor extended desktop

Karl Griffith
Booster
Yes, it needs to work from the same file for the comparison - an older version and a newer version. So the ifc you get from structural would need to include the architectural elements you want to check. In my case, I modeled structural walls in Archicad so I could control openings, etc., and of course structural modeled the same walls. I used this to check for their changes so I could modify my elements accordingly. So I would compare the previous version of the structural ifc with the current version of the ifc. But if their ifc doesn't have the elements you want to check, you would need to request a separate ifc with those elements.
ArchiCAD 22

Win 10

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