IFC Export - Dynamic Components IFC 2x3

If I assign a number in the same units as the native SketchUp file, e.g. millimetres, to IfcSite.RefElevation > IfcLengthMeasure in Dynamic Components, the export property when viewed in an IFC viewer displays 2.54 x (millimetres/1000). For example 19000mm displays as 482.6m?

Why might there be some sort of imperial factor conversion going on?

The classification is IFC 2x3, the export is with the IFC Manager extension and I’m using SketchUp2023.

Sketchup internal units are in inches. Have you tried to put 1mm instead of 1?

The mm method is used to convert from millimeters to inches.

It returns a Length value which is the same length as the given value. For example len = 25.4.mm returns 1 inch.

When the entry is changed to 19000mm instead of 19000, the export values remain the same:

  • DDScad viewer: Remains 482.6m
  • FZK viewer: Remains 482600.000000

I haven’t that problem. When I export and view the result with BimCollab Zoom my measures are in meters. (both Ifc 2x3 and 4)

Have you opened your IFC file with a text editor and checked the units?

My Ifc files has this:


I’ve isolated the issue to IFC Manager version 4.1.5 exporting schema IFC2x3.

With the SketchUp native file units set to millimetres, the values present after export:

  • IFC Manager 4.1.5 export IFC 2x3 = 482.6
  • IFC Manager 4.1.5 export IFC4 = 19000
  • IFC Manager 4.3.3 export IFC2x3 = 19000
  • IFC Manager 4.3.3 export IFC4 = 19000

The reason I am preferring Manager v4.1.5 is that v4.3.3 exports 2 IfcProject classes if you include IfcProject in the SketchUp model heirarchy (1 x default plus 1 x Outliner IfcProject).

I have 4.3.1 yet