topic Re: IfcCardinalPointReference in Collaboration with other software

IfcCardinalPointReference

GOBA — Tue, 10 Mar 2020 17:00:48 GMT

Hi,

Does anyone know if ArchiCAD support IfcCardinalPointReference? What I mean is if it’s possible to export the Column Reference Axis into an IFC. And, also, if ArhiCAD is able to understand the IfcCardinalPointReference when it merges an IFC.

This is the information of IfcCardinalPointReference from BuildinSmart:

https://standards.buildingsmart.org/IFC/RELEASE/IFC4/ADD2_TC1/HTML/schema/ifcmaterialresource/lexical/ifccardinalpointreference.htm

I have done some tests and it seems it does not export that information, but it could be I am not doing it correctly.

Regards,

GOBA

Re: IfcCardinalPointReference

Christophe Fortineau — Mon, 16 Mar 2020 10:01:41 GMT

Hello GOBA,

It seems to be possible only with ifc 4. So I tried with Archicad 23 the only one to be certified.
I have tried to export all ifc classes without being able to find "IfcCardinalPointReference" into my IFC (search with TextEdit software)
You can probably add it into your Archicad model.

Re: IfcCardinalPointReference

GOBA — Mon, 16 Mar 2020 17:14:52 GMT

Hi Christophe,

Thanks a lot. There is no such point in the IFC generated by ArchiCAD. I have opened it in txt, and there isn’t.

I am going to try to explain the purpose of my question.

If a client that works with ArchiCAD, model the architectural model, defining the Column Reference Axis, and export the IFC, I can use this IFC in my structural software. What my structural software can do is read the outline of the slabs, and the columns. But I would also like that it could read the Column Reference Axis, in case the architect has defined them.

I am a little confused with all the IFC information, and I don’t really know if I need IfcCardinalPointReference, or IfcCartesianPoint. There is no IfcCardinalPointReference in the IFC generated by ArchiCAD, and the IfcCartesianPoint is not the Column Reference Axis. I don’t really understand what ArchiCAD is doing with IfcCartesianPoint, it seems rare to me.

Thank you for your time

Re: IfcCardinalPointReference

Christophe Fortineau — Tue, 17 Mar 2020 10:41:30 GMT

Hello GOBA,

How I do to understand IFC and collaborate if I do not know how to do :
- I prepare a lot of ifc translators
- I try them with different viewers
- I share them with collaborators
- Finaly we make together a report about these IFC files and its parameters

Days after days I do not need to do it but about IFCCardinal, I am not able to help you 😕

Re: IfcCardinalPointReference

GOBA — Tue, 17 Mar 2020 11:33:54 GMT

Hi Christophe,

Thanks. The architects that are using ArchiCAD and work with me, don’t know much about translators. Since I have started using ArchiCAD, it’s me who is doing these tests. I think this should be the procedure, too.

What I think is that:
- Neither ArchiCAD, nor my structural software (CYPECAD) are using IfcCardinalPointReference.
- CYPECAD is exporting correctly the IfcCartesianPoint, taking into account the Column Reference Axis. ArchiCAD is not exporting that correctly.
- ArchiCAD does not read the IfcCartesianPoint from an IFC, and define from it the Column Reference Axis, in the ArchiCAD model.

I can be mistaken.

Re: IfcCardinalPointReference

Christophe Fortineau — Tue, 17 Mar 2020 14:17:23 GMT

GOBA,

All I know come from my experiences and Archicad-talk give me a lot of experiences.
Today I'm not able to give you a good solution because I never need to do this 😕

Re: IfcCardinalPointReference

GOBA — Tue, 17 Mar 2020 14:34:22 GMT

Hi! No problem , what I wrote in my last post was in case it could help someone.

If I find something else, or I confirm what I wrote, I come back!

Re: IfcCardinalPointReference

GOBA — Sat, 21 Mar 2020 08:45:27 GMT

Hi, I am quoting you, @mnguyen, because I would like to ask you about this matter.

I use an structural software, where I can define columns, as in Archicad, with its reference axis, like this:

In this case, the column size is 0.35x0.35, and it’s geometrical centre is (0,0), but its reference axis is located in (-0.175, -0.175), the bottom left corner.

I think the IFC is well generated, by my structural software. The origin of the IfcColumn is at (-0.175,-0.175,0). We can see this in this lines of the IFC:

#95= IFCCARTESIANPOINT((-0.175,-0.175,0.));
#96= IFCAXIS2PLACEMENT3D(#95,#62,#63);
#97= IFCLOCALPLACEMENT(#78,#96);
#99= IFCCOLUMN('2E8TTf6Rn2ZvtqXkW85M4i',#2,'P1 (35x35)','Rectangular. Hormig\X2\00F3\X0\n armado','35x35',#97,#101,$,
.COLUMN.);

So that point, (-0.175,-0.175,0), defines the origin of the column (the object coordinate system).

Now, the swept solid coordinate system (0,0,0):

#61= IFCCARTESIANPOINT((0.,0.,0.));
#64= IFCAXIS2PLACEMENT3D(#61,#62,#63);
#113= IFCEXTRUDEDAREASOLID(#112,#64,#62,3.);

Now the profile coordinate system:

#109= IFCCARTESIANPOINT((0.175,0.175));
#110= IFCAXIS2PLACEMENT2D(#109,#111);
#112= IFCRECTANGLEPROFILEDEF(.AREA.,$,#110,0.35,0.35);

The column has a 0.35 m square profile, and has a centerpoint coordinate of (0.175,0.175), which is 0.35/2. This offset explains why the object placement appears at the bottom left corner of the rectangular column. This is relative to the swept solid coordinate system (0,0,0) and the object coordinate system (-0.175,-0.175,0), which, in absolute coordinates, turns out to be the origin point of (0,0,0).

But, when I merge this IFC into ArchiCAD, the column generated does not have the column reference axis in the bottom left corner, but in the centre. Why is that?

On the other hand, if I model the same column in Archicad, with the reference axis on the bottom left corner, it appears the IFC generated by ArchiCAD does not contains the profile coordinate offset:

#182= IFCCARTESIANPOINT((0.,0.,0.));
#184= IFCAXIS2PLACEMENT3D(#182,#180,#178);
#185= IFCLOCALPLACEMENT(#160,#184);
#229= IFCCOLUMN('1cMxxcUd5Frhwr5oABIZHY',#30,'P4 (35x35)','Rectangular. Hormig\X2\00F3\X0\n armado',$,#185,#224,'665BBEE6-7A71-4FD6-BEB5-17228B4A3462');

Am I correct? In that case, why is that? It would be nice if the structural software could know the column reference axis defined.

Re: IfcCardinalPointReference

Minh Nguyen — Mon, 23 Mar 2020 14:05:01 GMT

Hi GOBA,

Thank you for sharing the issue!

Unfortunately, the IFC part is not something that I'm confident with, therefore I will need some help from my colleagues in the Technical Support team to answer you about this!

Thank you for your enthusiasm on this topic. Have a nice day, and stay safe!

Best regards,
Minh

Re: IfcCardinalPointReference

GOBA — Mon, 23 Mar 2020 17:38:30 GMT

Hi, thanks, and you too, stay safe! 

Re: IfcCardinalPointReference

Minh Nguyen — Fri, 27 Mar 2020 12:46:27 GMT

Hi GOBA,

With the help of my colleague, I've got an answer to your question. I'll try my best to explain it here:

In short, this is a limitation of ARCHICAD. The reason for that is, ARCHICAD deals with architectural models only, which means that it converts structural analysis models into architectural models as well.

The entity IfcRelConnectsWithEccentricity adds the definition of eccentricity to the connection between a structural member and a structural connection (representing either a node or support), which presents in the structural analysis but not architectural models.

In the future, we are working on connection between ARCHICAD's model and Structural Analysis Model. I hope that this feature will come soon to provide better support for communicating between the architect and structural engineer.

I hope this will answer your question. Feel free to ask me again if you have any questions!

Have a nice day!

Best regards,
Minh

Re: IfcCardinalPointReference

GOBA — Sat, 28 Mar 2020 07:24:27 GMT

Hi mnguyen,

Thanks for the information. I am not sure if this future feature will help me because my structural software is quite special: it works with physical model and it generates itself the analytical model, internally. The IFC generated is physical. A satisfactory workflow is not simple. Anyway, once ArhiCAD offers that feature, I’ll study it, just in case.

Have a nice weekend,

GOBA