IfcObjectPlacement

Semantic definitions at the entity

Entity definition

Abstract supertype for the special types defining the object coordinate system. The IfcObjectPlacement has to be provided for each product that has a shape representation.

The object placement can be given:

absolute, i.e. by an axis2 placement, relative to the world coordinate system,
relative, i.e. by an axis2 placement, relative to the object placement of another product,
by grid reference, i.e. by the virtual intersection and reference direction given by two axes of a design grid.

In any case the object placement has to unambiguously define the object coordinate system as either two-dimensional axis placement (IfcAxis2Placement2D) or three-dimensional axis placement (IfcAxis2Placement3D). The axis placement may have to be calculated.

Informal proposition

No two or more elements (subtypes of IfcProduct) shall share the same instance of IfcObjectPlacement.

HISTORY New entity in IFC Release 2x.

Attribute definitions

#	Attribute	Type	Cardinality	Description	A
	PlacesObject	IfcProduct @ObjectPlacement	S[1:1]	The IfcObjectPlacement shall be used to provide a placement and an object coordinate system for a single instance of IfcProduct.
	ReferencedByPlacements	IfcLocalPlacement @PlacementRelTo	S[0:?]	Placements that are given relative to this placement of an object.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description
IfcObjectPlacement
	PlacesObject	IfcProduct @ObjectPlacement	S[1:1]	The IfcObjectPlacement shall be used to provide a placement and an object coordinate system for a single instance of IfcProduct.
	ReferencedByPlacements	IfcLocalPlacement @PlacementRelTo	S[0:?]	Placements that are given relative to this placement of an object.

Formal representations

XSD Specification

 <xs:element name="IfcObjectPlacement" type="ifc:IfcObjectPlacement" abstract="true" substitutionGroup="ifc:Entity" nillable="true"/>

 <xs:complexType name="IfcObjectPlacement" abstract="true">

  <xs:complexContent>

   <xs:extension base="ifc:Entity"/>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcObjectPlacement

 ABSTRACT SUPERTYPE OF(ONEOF(IfcGridPlacement, IfcLocalPlacement));

 INVERSE

  PlacesObject : SET [1:1] OF IfcProduct FOR ObjectPlacement;

  ReferencedByPlacements : SET [0:?] OF IfcLocalPlacement FOR PlacementRelTo;

END_ENTITY;

 EXPRESS-G diagram