export a spline to dxf or ifc

[bernd]

I would like to transfer a spline solid from FreeCAD to Allplan Nemetschek. At the moment this is not possible by IFC since on Import Allplan would triangulate nearly any IFC geometry it gets (apart from sprecial defined reinforcement).

The idea is to just transfer the 3D spline and make the sweep again in Nemetschek Allplan. Does sound very simple but it is not. Neither ifc nor dxf seam to support a 3D spline

Anyone an idea, how I can transfer the spline as a spline ?

cheers bernd

spline.FCStd

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[microelly2]

Do you have an example how a spline is written in ifc?
writing a textfile with the data of your courve should not be to hard,
but I don't know the inner format of ifc by example.

[yorik]

I actually don't know of any file format that would support a 3d curve faithfully...

[bernd]

I actually don't know of any file format that would support a 3d curve faithfully...

apart from step and brep ... They both do. Ich can export and import the edge as often as I want.

How about a 3D polyline and dxf or ifc? I would create the spline new in Allplan but than I would have something to visualize compare with.

[bernd]

Do you have an example how a spline is written in ifc?
writing a textfile with the data of your courve should not be to hard,
but I don't know the inner format of ifc by example.

The problem seams to be what Yorik said. We are able to write the data to a text file but non of the File Formats Allplan can import seams to be able to handle this.

[bernd]

I have been playing around a bit. Even if there would be a format which supports 3D spline, it seams Allplan 2017 does not support 3D-spline rebars. The gone make a polyline out of the spiral rebar in their software. But I'm not 100 % sure because you can not analyse every geometry in Allplan. Means eventually I'm fine if I would be able to export the spline as 3D-Plyline to dxf or ifc

Anyway I made it the other way around and made sprial rebar in Allplan and exported to ifc. It seams either ifcopenshell or FreeCAD has some problems with it. But ifx++ too ...

spiralrebar.ifc

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[microelly2]

I found this example
https://www.cms.bgu.tum.de/de/component ... :ifctunnel
https://www.cms.bgu.tum.de/images/forsc ... v_LoD1.ifc
and the spec here
http://www.buildingsmart-tech.org/ifc/I ... hknots.htm

Can Allplan read this file?

[bernd]

https://www.cms.bgu.tum.de/images/forsc ... v_LoD1.ifc
Can Allplan read this file?

Nice find, but Allplan does not seam to support this entity. I'm gone check with the support, but this may take a while.

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[yorik]

In IFC I'm not sure we have 3D splines available... I will have a look.
But in any case, to have a 3D object based on such a curve in IFC, it would be either triangulated, or a nurbs surface. But nurbs surfaces were only introduced in IFC4, and I don't think many apps already support it... Outside FreeCAD (the credit goes to ifcopenshell of course)

In DXF, if autocad can do it, then it should be supported. Anyone has an autocad at hand to test?