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Definition from buildingSMART: The IfcProjectionElement is a specialization of the general feature element to represent projections applied to building elements. It represents a solid attached to any element that has physical manifestation. Projections must be handled by all sectors and disciplines in AEC/FM industry, therefore the interoperability for opening elements is provided at this high level.

EXAMPLE: A wall projection such as a pilaster strip is handled by IfcProjectionElement

An IfcProjectionElement has to be inserted into a building element (all subtypes of IfcBuildingElement) by using the IfcRelProjectsElement relationship. It is also directly linked to the spatial structure of the project (and here normally to the IfcBuildingStorey) by using the IfcRelContainedInSpatialStructure relationship.

HISTORY New entity in Release IFC2x Edition 2.

Geometry Use Definitions:

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

Local Placement

The local placement for IfcOpeningRecess 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.

Swept Solid Representation

The geometric representation of IfcProjectionElement is defined using the swept area solid geometry. The attribute RepresentationType of IfcShapeRepresentation should have the value 'SweptSolid'. The RepresentationIdentifier of IfcShapeRepresentation should then have the value 'Body'. The following additional constraints apply to the swept solid representation:



The following interpretation of dimension parameter applies for rectangular projection:

  • IfcRectangleProfileDef.YDim interpreted as projection width
  • IfcRectangleProfileDef.XDim interpreted as projection height
  • IfcExtrudedAreaSolid.Depth is interpreted as projection depth

NOTE: Rectangles are now defined centric, the placement location has to be set:

  • IfcCartesianPoint(XDim/2,YDim/2)

NOTE: The local placement directions for the IfcProjectionElement are only given as an example, other directions are valid as well.

Brep Representation

The general b-rep geometric representation of IfcProjectionElement is defined using the Brep geometry. The Brep representation allows for the representation of complex element shape. It is ensured by assigning the value 'Brep' to the RepresentationType attribute of IfcShapeRepresentation The RepresentationIdentifier of IfcShapeRepresentation should then have the value 'Body'.

EXPRESS specification:

ENTITY IfcProjectionElement
SUBTYPE OF ( IfcFeatureElementAddition);

Inheritance graph

ENTITY IfcProjectionElement;
GlobalId  :  IfcGloballyUniqueId;
OwnerHistory  :  IfcOwnerHistory;
Name  :  OPTIONAL IfcLabel;
Description  :  OPTIONAL IfcText;
ENTITY IfcObjectDefinition;
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;
IsDefinedBy  :  SET OF IfcRelDefines FOR RelatedObjects;
ENTITY IfcProduct;
ObjectPlacement  :  OPTIONAL IfcObjectPlacement;
Representation  :  OPTIONAL IfcProductRepresentation;
ReferencedBy  :  SET OF IfcRelAssignsToProduct FOR RelatingProduct;
ENTITY IfcElement;
Tag  :  OPTIONAL IfcIdentifier;
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 IfcFeatureElement;
ENTITY IfcFeatureElementAddition;
ProjectsElements  :  IfcRelProjectsElement FOR RelatedFeatureElement;
ENTITY IfcProjectionElement;