IFC 4.3.0.1 (IFC4X3) development

# 8.7.3.15 IfcObjectPlacement

ABSTRACT This definition may not be instantiated

## 8.7.3.15.1 Semantic definition

IfcObjectPlacement is an 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: by an axis2 placement, relative to the world coordinate system,
• relative: by an axis2 placement, relative to the object placement of another product,
• by grid reference: by the virtual intersection and reference direction given by two axes of a design grid,
• linear placement: by distance along a curve, with possible offsets.

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.

## 8.7.3.15.4 Formal representation

ENTITY IfcObjectPlacement
ABSTRACT SUPERTYPE OF (ONEOF
(IfcGridPlacement
,IfcLinearPlacement
,IfcLocalPlacement));
PlacementRelTo : OPTIONAL IfcObjectPlacement;
INVERSE
PlacesObject : SET [0:?] OF IfcProduct FOR ObjectPlacement;
ReferencedByPlacements : SET [0:?] OF IfcObjectPlacement FOR PlacementRelTo;
END_ENTITY;