IfcGeometricSet

Semantic definitions at the entity

Entity definition

Definition from ISO/CD 10303-42:1992: This entity is intended for the transfer of models when a topological structure is not available.

The IfcGeometricSet is used for the exchange of shape representations consisting of (2D or 3D) points, curves, and/or surfaces, which do not have a topological structure (such as connected face sets or shells) and are not solid models (such as swept solids, CSG or Brep)

NOTE: Corresponding STEP entity: geometric_set. The derived attribute Dim has been added at this level and was therefore demoted from the geometric_representation_item. Please refer to ISO/IS 10303-42:1994, p. 190 for the final definition of the formal standard.

HISTORY: New entity in IFC Release 2x.

Attribute definitions

#	Attribute	Type	Cardinality	Description	A
1	Elements	IfcGeometricSetSelect	S[1:?]	The geometric elements which make up the geometric set, these may be points, curves or surfaces; but are required to be of the same coordinate space dimensionality.	X
	Dim :=Elements[1].Dim	IfcDimensionCount	[1:1]	The space dimensionality of this class, it is identical to the first element in the set. A where rule ensures that all elements have the same dimensionality.	X

Formal Propositions

Rule	Description
WR21	All elements within a geometric set shall have the same dimensionality.

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRepresentationItem
IfcGeometricRepresentationItem
IfcGeometricSet
1	Elements	IfcGeometricSetSelect	S[1:?]	The geometric elements which make up the geometric set, these may be points, curves or surfaces; but are required to be of the same coordinate space dimensionality.	X
	Dim :=Elements[1].Dim	IfcDimensionCount	[1:1]	The space dimensionality of this class, it is identical to the first element in the set. A where rule ensures that all elements have the same dimensionality.	X

Formal representations

XSD Specification

 <xs:element name="IfcGeometricSet" type="ifc:IfcGeometricSet" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>

 <xs:complexType name="IfcGeometricSet">

  <xs:complexContent>

   <xs:extension base="ifc:IfcGeometricRepresentationItem">

    <xs:sequence>

     <xs:element name="Elements">

      <xs:complexType>

       <xs:group ref="ifc:IfcGeometricSetSelect" maxOccurs="unbounded"/>

       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcGeometricSetSelect"/>

       <xs:attribute ref="ifc:cType" fixed="set"/>

       <xs:attribute ref="ifc:arraySize" use="optional"/>

      </xs:complexType>

     </xs:element>

    </xs:sequence>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcGeometricSet

 SUPERTYPE OF(IfcGeometricCurveSet)

 SUBTYPE OF (IfcGeometricRepresentationItem);

  Elements : SET [1:?] OF IfcGeometricSetSelect;

 DERIVE

  Dim : IfcDimensionCount := Elements[1].Dim;

 WHERE

  WR21 : SIZEOF(QUERY(Temp <* Elements |
  Temp.Dim <> Elements[1].Dim))
= 0;
END_ENTITY;

 EXPRESS-G diagram