IFC Export from FreeCAD

[yorik]

Wow... would Allplan be INCAPABLE of exporting such a wall? Can you try creating a similar one from scratch? I'd be curious to see how IfcOpenShell likes it...

[bernd]

Wow... would Allplan be INCAPABLE of exporting such a wall? Can you try creating a similar one from scratch? I'd be curious to see how IfcOpenShell likes it...

Mhh, the problem is. You wouldn't belive it because most of the bridges in Germany and Switzerland are made using Allplan (may be Belgium too.). Allplan is not capable of handle solids with curves. It triangulates everything to polygones. Like the wall here too. A circle was used to create the wall.

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[bernd]

Yeah, look at the funny sphere and cylinder. As soon as one converts 2D curves to 3D data it gets triangulated to polygons. But to be honest I never needed real curved solids. The polygons are just precisly enought in buildings I do (Seams I 'm to expensive for Zaha Hadid or Santiago Calatrava ). I remember the bridge guys had problems in formwork drawings because one gets differences in cm if you have a bridge with a diameter of a few dozens meters and that get triagulated to polygons. But as I heard Allplan is gone change this in one of the next versions. Yeah modelling is not the strength of allplan. One of the reasons I'm here. It's called Allplan not Allmodel and Allplan is really strong in individual drawing plots from your modell.

[yorik]

Wow, amazing! We could do better! Of course we need to be able to do Zaha Hadid projects in FreeCAD Otherwise, how will we convince her to use FreeCAD...

[Patrick]

Bernd, could you give a test spin to this file when you have a moment? It's a test at exporting composite profiles (lines + arcs) from FreeCAD... It opens fine in ifc++, solibri, tekla and the karlsruhe viewer, but fails with ifcopenshell itself. I don't see what's wrong, maybe you'll find more clues... This is the content of the file:

testcurves.ifc

Thanks!

Hi

Just joined your little thread regarding export from FreeCAD to IFC format.
I tested the "testcurves.ifc" in Tekla structures 20.0 and it failed to generate the parts.

I don´t know if it´s Tekla that can´t interpret the file correctely or if the export file isn´t 100% according to IFC format.
Just so that you know

And as persons earlier noted TeklaBIMSight doesn´t show anything.

[bernd]

Just joined your little thread regarding export from FreeCAD to IFC format.
I tested the "testcurves.ifc" in Tekla structures 20.0 and it failed to generate the parts.

I don´t know if it´s Tekla that can´t interpret the file correctely or if the export file isn´t 100% according to IFC format.
Just so that you know

And as persons earlier noted TeklaBIMSight doesn´t show anything.

Hi Patrick,

welcome to the community of FreeCAD and thanks for testing the file in Tekla Structures. The problem with this version of testcurves.ifc has allready been found. Saso pointed out the problem is some roundings, see forum post viewtopic.php?f=23&t=5125&start=90#p54339

But there will be soon a new version of the testfile, probably. There has been a commit regarding the issue, commit 3642 (https://github.com/FreeCAD/FreeCAD_sf_m ... 4d63d4b2ef) so stay tuned ...

May I ask you in which field are you woring with Tekla Structures. Is it Steel constructions or concrete constructions ?

Kind regards Bernd

... your little thread ...

[Patrick]

I´m been working with Tekla since 1992, then called Xsteel.
I´m now working as a superuser in a multinational company.

I´m working with detail design of steel, Cast in place and some precast concrete.

I found your software when looking into IFC export and Import and trying to see why there are differences in export and import of IFC.
One of the problem is , as I see it, that software interpret the IFC files differntly, like a bad translator of a book.

I´ve looked at ifcOpenshell that have mad the best solution so far to interpret i.e ifc import to 3D studio MAX.

[yorik]

It is really hard to obtain IFC files that work 100% in all applications. Even files exported by big commercial apps often fail when importing them in other apps. Of course sticking to the IFC schema helps, but it is not sufficient... We could easily export everything as Breps, ensuring 100% conformity, but then the exported file would be heavy and almost impossible to edit. The idea is to use a maximum of more "intelligent" geometry, but that's where the problems begin

Anyway, the more people we are here to test, the best we can do. Thanks for joining!

I've been working more on curves, and discovered a bug in IfcOpenShell, it expects files coded in meters, so its precision value for sewing shapes is about 0.0001. If we work in millimeters, this becomes much too narrow, and the small gaps between curved and straight segments fall below this treshold. With that corrected, all curved examples I made the last days now open correctly in FreeCAD and all apps I tested. Only revit complains, but even so imports correctly.

I'm now testing code to treat openings as separate objects, but it still doesn't work perfectly. The testhouse2 already uses that mechanism.

[bernd]

Just tested the newest testhouse2.ifc one from June 2. TeklaBimSight opens the file, displays alle object including the bullet window and the door of the curved wall but misses the curved wall itself. Allplan imports just everything fine (the allplan way, as polygons)

@Yorik. You wouldn't mind exporting the curved wall and the door only ?

[bernd]

I´m been working with Tekla since 1992 ...

Wow 22 years of Tekla experience, would like to have that for FreeCAD

I´m working with ... and some precast concrete ...

I'm structural engineer working in the field of reinforced concrete. I work with Nemetschek Allplan and of course FreeCAD. I'd be curious how Tekla handles Reinforcement Bars and Built-in-parts like plates, ancors and other armatures. You wouldn't mind to contribute some basic example of Tekla Export to ifc for testing in FreeCAD and IfcOpenShell.

Bernd