IfcAxis1Placement

Semantic definitions at the entity

Entity definition

Definition from ISO/CD 10303-42:1992: The direction and location in three dimensional space of a single axis. An axis1_placement is defined in terms of a locating point (inherited from placement supertype) and an axis direction: this is either the direction of axis or defaults to (0.0,0.0,1.0). The actual direction for the axis placement is given by the derived attribute z (Z).

NOTE: Corresponding STEP name: axis1_placement, please refer to ISO/IS 10303-42:1994, p. 28 for the final definition of the formal standard.

HISTORY: New entity in IFC Release 1.5

Illustration:

Definition of the IfcAxis1Placement within the three-dimensional coordinate system.

Attribute definitions

#	Attribute	Type	Cardinality	Description	A
2	Axis	-		This attribute is out of scope for this model view definition and shall not be set.
	Z :=NVL (IfcNormalise(Axis), IfcRepresentationItem() \|\| IfcGeometricRepresentationItem () \|\| IfcDirection([0.0,0.0,1.0]))	IfcDirection	[1:1]	The normalized direction of the local Z axis. It is either identical with the Axis value, if given, or it defaults to [0.,0.,1.]	X

Formal Propositions

Rule	Description
WR1	The Axis when given should only reference a three-dimensional IfcDirection.
WR2	The Cartesian point defining the Location shall have the dimensionality of 3.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRepresentationItem
IfcGeometricRepresentationItem
IfcPlacement
1	Location	IfcCartesianPoint	[1:1]	The geometric position of a reference point, such as the center of a circle, of the item to be located.	X
	Dim :=Location.Dim	IfcDimensionCount	[1:1]	The space dimensionality of this class, derived from the dimensionality of the location.	X
IfcAxis1Placement
2	Axis	-		This attribute is out of scope for this model view definition and shall not be set.
	Z :=NVL (IfcNormalise(Axis), IfcRepresentationItem() \|\| IfcGeometricRepresentationItem () \|\| IfcDirection([0.0,0.0,1.0]))	IfcDirection	[1:1]	The normalized direction of the local Z axis. It is either identical with the Axis value, if given, or it defaults to [0.,0.,1.]	X

Formal representations

XSD Specification

 <xs:element name="IfcAxis1Placement" type="ifc:IfcAxis1Placement" substitutionGroup="ifc:IfcPlacement" nillable="true"/>

 <xs:complexType name="IfcAxis1Placement">

  <xs:complexContent>

   <xs:extension base="ifc:IfcPlacement"/>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcAxis1Placement

 SUBTYPE OF (IfcPlacement);

  Axis : OPTIONAL IfcStrippedOptional;

 DERIVE

  Z : IfcDirection := NVL (IfcNormalise(Axis), IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcDirection([0.0,0.0,1.0]));

 WHERE

  WR1 : (NOT (EXISTS (Axis))) OR (Axis.Dim = 3);
  WR2 : SELF\IfcPlacement.Location.Dim = 3;
END_ENTITY;

 EXPRESS-G diagram