IfcVirtualElement

Definition from IAI: A special element used to provide imaginary boundaries, such as between two adjacent, but not separated, spaces. Virtual elements are usually not displayed and does not have quantities and other measures. Therefore IfcVirtualElement does not have material information and quantities attached.

NOTE The main purpose of IfcVirtualElement is the provision of a virtual space boundary. The IfcVirtualElement provides the 2D curve or 3D surface representation of the virtual space connection and is referenced by two instances of IfcRelSpaceBoundary, each pointing to one of the two adjacent IfcSpaces.

HISTORY New entity in IFC Release 2x2 Addendum 1.

IFC2x2 ADDENDUM CHANGE: The entity IfcVirtualElement has been added. Upward compatibility for file based exchange is guaranteed.

Geometry Use Definitions

The geometric representation of any IfcVirtualElement is given by the IfcProductDefinitionShape and IfcLocalPlacement allowing multiple geometric representations.

Local Placement

The local placement for IfcVirtualElement is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations.

The PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the local placement of the same IfcSpatialStructureElement that is used in the ContainedInStructure inverse attribute or to a referenced spatial structure element at a higher level.
If the relative placement is not used, the absolute placement is defined within the world coordinate system.

Geometric Representations

Currently, the use of 'FootPrint' and 'Surface' representation is supported.

Two-dimensional Representation using foot print representation

The 2D geometric representation of IfcVirtualElement is defined using the 'FootPring' or 'Surface' representation. The following attribute values should be inserted

IfcShapeRepresentation.RepresentationIdentifier = 'FootPrint'.
IfcShapeRepresentation.RepresentationType = 'Curve2D' or 'GeometricCurveSet' .

The following constraints apply to the 2D curve representation:

Curve: IfcPolyline, IfcTrimmedCurve or IfcCompositeCurve

Three-dimensional Representation using surface model representation

The 3D geometric representation of IfcVirtualElement is defined using the 'SurfaceModel' geometry. The following attribute values should be inserted

IfcShapeRepresentation.RepresentationIdentifier = 'Surface'.
IfcShapeRepresentation.RepresentationType = 'GeometricSet .

The following constraints apply to the 3D surface representation:

Surface: IfcSurfaceOfLinearExtrusion
Profile: IfcArbitraryOpenProfileDef
Extrusion: The extrusion direction shall be vertically, i.e., along the positive Z Axis of the co-ordinate system of the containing spatial structure element.

EXPRESS specification:

ENTITY IfcVirtualElement

SUBTYPE OF (

IfcElement);

END_ENTITY;

Inheritance graph

ENTITY IfcVirtualElement;

ENTITY IfcRoot;

GlobalId

IfcGloballyUniqueId;

OwnerHistory

IfcOwnerHistory;

Name

OPTIONAL IfcLabel;

Description

OPTIONAL IfcText;

ENTITY IfcObjectDefinition;

INVERSE

HasAssignments

SET OF IfcRelAssigns FOR RelatedObjects;

IsDecomposedBy

SET OF IfcRelDecomposes FOR RelatingObject;

Decomposes

SET [0:1] OF IfcRelDecomposes FOR RelatedObjects;

HasAssociations

SET OF IfcRelAssociates FOR RelatedObjects;

ENTITY IfcObject;

ObjectType

OPTIONAL IfcLabel;

INVERSE

IsDefinedBy

SET OF IfcRelDefines FOR RelatedObjects;

ENTITY IfcProduct;

ObjectPlacement

OPTIONAL IfcObjectPlacement;

Representation

OPTIONAL IfcProductRepresentation;

INVERSE

ReferencedBy

SET OF IfcRelAssignsToProduct FOR RelatingProduct;

ENTITY IfcElement;

Tag

OPTIONAL IfcIdentifier;

INVERSE

FillsVoids

SET [0:1] OF IfcRelFillsElement FOR RelatedBuildingElement;

ConnectedTo

SET OF IfcRelConnectsElements FOR RelatingElement;

HasCoverings

SET OF IfcRelCoversBldgElements FOR RelatingBuildingElement;

HasProjections

SET OF IfcRelProjectsElement FOR RelatingElement;

HasStructuralMember

SET OF IfcRelConnectsStructuralElement FOR RelatingElement;

ReferencedInStructures

SET OF IfcRelReferencedInSpatialStructure FOR RelatedElements;

HasPorts

SET OF IfcRelConnectsPortToElement FOR RelatedElement;

HasOpenings

SET OF IfcRelVoidsElement FOR RelatingBuildingElement;

IsConnectionRealization

SET OF IfcRelConnectsWithRealizingElements FOR RealizingElements;

ProvidesBoundaries

SET OF IfcRelSpaceBoundary FOR RelatedBuildingElement;

ConnectedFrom

SET OF IfcRelConnectsElements FOR RelatedElement;

ContainedInStructure

SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

ENTITY IfcVirtualElement;

END_ENTITY;