Does 'Perform Quantity Take-off' work on a type?

theoryshaw

Dumb question, let's say you have an IfcWindowType, and you run the 'Perform Quantity Take-off', isn't it supposed to auto populate the Qto_WindowBaseQuanitities? It doesn't seem to work for me.

It works when you select the instance, but not the type.

Am i missing something?

falken10vdl

You have raised a very good point. I have seen the same.
In fact, shouldn't some quantities be inherited by instances from the type they belong? Like depth in a wall?
So in general for instances, some quantities need ro be computed for each instance itself and some other should just be linked to the type they belong to?
Thanks!

Massimo

If you compile manually the PSet Qto of the type (instead of automatically perform qto), do the instances inherit the pset?

steverugi

@theoryshaw
very interesting, for instance IfcWindowType does have a Qto, per https://standards.buildingsmart.org/
like others (IfcDoor, etc) it's the same Qto_*BaseQuantities set
Feature request?

steverugi

@Massimo

If you compile manually the PSet Qto of the type (instead of automatically perform qto), do the instances inherit the pset?

no they don't
by looking at the ifc text and schema both IfcWindowType and IfcWindow have a separate IfcElementQuantity

• for the type it is an entity directly connected to attribute 6 HasProperties
• for the instance it's an inverse one managed by IsDefinedBy > IfcRelDefinesByProperties > RelatingPropertyDefinition