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.
ArchiCAD user since November 2109
AC24, Windows 10