FreeMVD_Mirror/IFC_roundtrip_specifications.md

IFC roundtripping specifications

This file lists "exercises" to be performed by a BIM application to achieve adequate round-tripping with IFC files. The application should successfully complete all the steps.

1. importing and exporting a simple extrusion

The application should be able to export and import an IFC file containing one IfcBuildingElementProxy entity, with one representation, which is an IfcExtrudedAreaSolid, based on an IfcArbitraryClosedProfileDef made of an IfcPolyline, like the example below:

  #20= IFCBUILDINGELEMENTPROXY('0ohBfsArr3ruXYxacT4yl5',#1,'NOTDEFINED',$,$,#2,#21,$,.NOTDEFINED.);
    #21= IFCPRODUCTDEFINITIONSHAPE($,$,(#22));
      #22= IFCSHAPEREPRESENTATION(#9,'Body','SweptSolid',(#23));
        #23= IFCEXTRUDEDAREASOLID(#24,$,#25,2000.);
          #24 = IFCARBITRARYCLOSEDPROFILEDEF(.AREA., $, #26);
            #26 = IFCPOLYLINE((#27, #28, #29, #30));
              #27 = IFCCARTESIANPOINT((0., 0.));
              #28 = IFCCARTESIANPOINT((1000., 0.));
              #29 = IFCCARTESIANPOINT((1000., 1000.));
              #30 = IFCCARTESIANPOINT((0., 1000.));
          #25= IFCDIRECTION((0.,0.,1.));

Import criteria

• The profile position and extrusion direction are correct
• The extrusion can be changed after import
• The base polyline can be edited after import

Export criteria

• The exported IFC file contains an IfcBuildingElementProxy, with an IfcExtrudedAreaSolid as its representation and an IfcArbitraryClosedProfileDef made of an IfcPolyline as its profile
• The position and extrusion direction are correct when the IFC file is viewed with ifc++

Results

	BlenderBIM	FreeCAD	Revit	ArchiCAD	BricsCAD
passed?		yes
exported file:		simple extrusion.ifc
imported file:		simple extrusion.FCStd

2. importing and exporting non-vertical extrusions

The application should be able to export and import an IFC file containing three IfcBuildingElementProxy entities, each with one representation, which is an IfcExtrudedAreaSolid, each based on IfcArbitraryClosedProfileDef made of an IfcPolyline, like the example below. One profile should lie on the XY plane, one in the YZ plane, and a third on a plane made of one of the former rotated 45° along the Y axis. Extrusion directions should be normal to the profiles.

  #20= IFCBUILDINGELEMENTPROXY('0ohBfsArr3ruXYxacT4yl5',#1,'NOTDEFINED',$,$,#2,#21,$,.NOTDEFINED.);
    #21= IFCPRODUCTDEFINITIONSHAPE($,$,(#22));
      #22= IFCSHAPEREPRESENTATION(#9,'Body','SweptSolid',(#23));
        #23= IFCEXTRUDEDAREASOLID(#24,#31,#25,2000.);
          #24 = IFCARBITRARYCLOSEDPROFILEDEF(.AREA., $, #26);
            #26 = IFCPOLYLINE((#27, #28, #29, #30));
              #27 = IFCCARTESIANPOINT((0., 0.));
              #28 = IFCCARTESIANPOINT((1000., 0.));
              #29 = IFCCARTESIANPOINT((1000., 1000.));
              #30 = IFCCARTESIANPOINT((0., 1000.));
          #25= IFCDIRECTION((0.,0.,1.));
          #31= IFCAXIS2PLACEMENT3D(#32,#33,#34);
            #32= IFCDIRECTION((0.7071,0.,-0.7071));
            #33= IFCDIRECTION((0.7071,0.,0.7071));
            #34= IFCCARTESIANPOINT((1000.,0.,2000.));

Import criteria

• The extrusion directions and profile positions are correct
• The extrusions can be changed after import
• The base polylines can be edited after import

Export criteria

• The exported IFC file contains three IfcBuildingElementProxy, each with an IfcExtrudedAreaSolid as its representation and an IfcArbitraryClosedProfileDef made of an IfcPolyline as its profile.
• The positions and extrusion directions are correct when the IFC file is viewed with ifc++

Results

	BlenderBIM	FreeCAD	Revit	ArchiCAD	BricsCAD
passed?		yes
exported file:		multiple extrusions.ifc
imported file:		multiple extrusions.FCStd