||extended coordination view
||05. May 2006
||ISG meeting Munich
|summary||geometry for decomposed elements shall either be given at the element container or at the element part level|
The IFC specification allows all subtypes of IfcBuildingElement (and other) to act as a container entity, i.e. to be a decomposed element having parts. This is expressed by an IfcRelAggregates relationship entity pointing to the container with RelatingObject and it referenced by the inverse attribute IsDecomposedBy. An example is a roof, containing two roof slabs:
- IfcRoof <--RelatingObject-- IfcRelAggregates --RelatedObjects--> IfcSlab (PredefinedType=.ROOF.)
The following agreement is made:
- If the building element acts as a container, i.e. has parts associated, and those parts have own shape representations, then the container shall have no shape representation.
initiator: Coordination View V2.0 model view definition development
The requirement only concerns the shape representation of the container with RepresentationIdentifier = "Body". The container may have an own shape representation (e.g. of RepresentationIdentifier = "Axis" or "Box") even if the parts have the shape representation with RepresentationIdentifier = "Body".
Figure: correct assignment of 'Body' shape representation to parts only