IFC Converter

Table of Contents

• Overview
• Scope
• Mapping
  • Import mapping
    • Product structure
    • Topology
  • Export mapping
    • Product structure
• Parameters
  • Importer parameters

Overview

IFC_Reader can read IFC files of versions 2X3 and 4 (up to 4.3). Only models saved as physical STEP files (ISO 10303-21, .ifc extension) are supported. ifcXML and ifcZIP varieties are currently not supported. IFC_Writer can write IFC files of version 2X3.

Scope

Import	Export
B-Rep representations assembly structure names user-defined properties colors layers	B-Rep representations assembly structure names user-defined properties colors layers

Mapping

Import mapping

Tables below show how IFC entities are mapped to CAD Exchanger entities after import.

Product structure

IFC Entity	CAD Exchager Entity	Note
IfcProject	ModelData_Assembly
IfcSite
IfcBuilding
IfcBuildingStorey
IfcSpace
Subtypes of IfcElement	One of: ModelData_Part ModelData_Assembly	ModelData_Assembly is used for entities representing non-leaf nodes in the hierarchy (either through aggregation relationship or by containing mapped representations enabling geometry sharing). For leaf nodes with simple representations ModelData_Part is used. Subtypes of IfcElement are too numerous to list all of them here. Common ones are IfcWall, IfcSlab, IfcBeam, IfcBuildingElementProxy.
IfcRepresentation	ModelData_Part	Only for mapped representations that define the geometry shared between multiple elements.

Topology

IFC Entity	CAD Exchanger Entity	Note
IfcFacetedBrep	ModelData_Body with type equal to ModelData_BT_Solid
IfcSweptAreaSolid		Concrete types are IfcExtrudedAreaSolid, IfcRevolvedAreaSolid, IfcSurfaceCurveSweptAreaSolid.
IfcSweptDiskSolid
IfcCsgPrimitive3D		Concrete types are IfcBlock, IfcSphere, IfcRightRectangularPyramid, IfcRightCircularCylinder and IfcRightCircularCone.
IfcBooleanResult
IfcFaceBasedSurfaceModel	ModelData_Body with type equal to ModelData_BT_Sheet
IfcShellBasedSurfaceModel
IfcGeometricSet	A collection of ModelData_Body instances with ModelData_BT_Sheet, ModelData_BT_Wireframe, ModelData_BT_Acorn types.
IfcConnectedFaceSet	ModelData_Shell	Concrete types are IfcOpenShell and IfcClosedShell.
IfcPolygonalFaceSet	ModelData_Shell
IfcTriangulatedFaceSet
IfcFace	ModelData_Face
IfcPolyLoop	ModelData_Wire
Subtypes of IfcProfileDef	ModelData_Wire	Concrete types such as IfcArbitraryClosedProfileDef, IfcLShapeProfileDef, IfcDerivedProfileDef and others.
IfcEdge	ModelData_Edge

Export mapping

Tables below show how CAD Exchanger entities are mapped to IFC entities after export.

Product structure

CAD Exchager Entity	IFC Entity
ModelData_Assembly	IfcElementAssembly
ModelData_Part	IfcBuildingElementProxy

Parameters

Importer parameters

The IFC import parameters are controlled by IFC_ReaderParameters. The following table contains a list of parameters for IFC import:

Parameter	Default value	Description
IgnoreVirtualObjects()	true	Specifies whether the geometry of virtual objects should be skipped or imported. Currently only IfcSpace and IfcOpeningElement are considered to be virtual objects. This parameter concerns only the import of geometry, i.e. if an instance of IfcSpace also serves as a parent for one or more products, it will have a corresponding node in the product structure regardless of the value of this parameter.
ReadGlobalIds()	false	Specifies whether the IFC Global IDs should be saved as properties of corresponding product structure elements. Most of IFC structural entities bear the Global ID, which may be used to uniquely identify these elements. With ReadGlobalIds() enabled they are saved in ModelData_PropertyTable of corresponding product structure element and can be queried like this: ModelData_PropertyTable aTable = aPart.Properties(); /* 'aPart' is an instance of ModelData_Part accessed after IFC import */ Base_UTF16String anID; aTable.FindProperty (IFC_Reader::GlobalIdPropertyName(), anID);