||extended coordination view
||23. May 2007
||ISG meeting in Espoo
|summary||agreement on having the containment tree and the relative placement tree identical for spatial elements|
The spatial containment of IfcSpatialStructureElement forms a tree, and the local relative placement of IfcSpatialStructureElement forms another tree - both trees should be identical (i.e. if an IfcBuildingStorey is contained in #201=IFCBUILDING, then the IfcBuildingStorey.ObjectPlacement.PlacementRelTo shall point to the same instance #201=IFCBUILDING.
Figure: the containment and local placement trees.
Added 2010 in official buildingSMART certification 2.0 program
- the uppermost spatial structure element, either an IfcSite, or an IfcBuilding, that is directly assigned to the IfcProject through Decomoses.RelatingObject, shall have no relative placement.
- the placement of the uppermost spatial structure element is provided by IfcLocalPlacement with PlacementRelTo = NIL.