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.

> 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 'FootPrint' 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
HasStructuralMember | : | SET OF IfcRelConnectsStructuralElement FOR RelatingElement;
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;
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;