New files spatial container

[maxfb87]

I create a new blender file, i press "Create Project" from "IFC Project" menu and correctly IfcSite/IfcBuilding/IfcBuildingStorey are created.
But, is it correct that if i select the IfcBuildingStorey object it is shown that "The object is not spatially contained" in "IFC Spatial Container Menu"?

Shouldn't it show the "IfcBuilding" in this case?
Also, the same happens with others spaces from others files so i'm curious to know if it is correct...
Massimo

[Moult]

This is correct. The building storey is not "contained in" the building. Instead, it is "aggregated" in the building.

I guess in casual language the different is not so clear. Contained in vs aggregated into are both parent-child relationships and we are so used to understanding what it means through context. However in IFC they have special meanings:

• Contained In: a physical (i.e. you can touch it) element is located within a spatial (i.e. imaginary concept, not physical) element
• Aggregated: an element is the sum of its parts [... of the same type of element ...]. E.g. a physical element is made out of many other physical elements. A spatial element is made out of other spatial elements (a building is divided into levels).
• Nested: an element is part of a larger element, specifically through a particular connection point which cannot be moved (such as a socket, port, etc). This implies that when the larger element moves, the parts must move with it (in contrast, containment and aggregated parts and whole may move independently).
• Features: an element voids or protrudes a parent element, and its existence depends wholly on the parent element.

[maxfb87]

Thanks for explanation! I thought that, in the past, a building storey was contained in a building but i guess i'm wrong.
Thanks again!