IfcProjectionElement

Definition from IAI: 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 linked to a building element (all subtypes of IfcBuildingElement) by using the IfcRelProjectsElement relationship. Its existence depends on the existence of the master element.
It is also directly linked to the spatial structure of the project (and here normally to the IfcBuildingStorey) by using the IfcRelContainedInSpatialStructure relationship. It should not be linked directly to the spatial structure of the project, i.e. the inverse relationship ContainedInStructure shall be NIL. It is assigned to the spatial structure through the element it projects.

> HISTORY New entity in Release IFC2x Edition 2.

Quantity Use Definition:

The quantities relating to the IfcProjectionElement are defined by the IfcElementQuantity and attached by the IfcRelDefinesByProperties. The following quantities are foreseen, but will be subjected to the local standard of measurement:

Name | Description | Value Type
NominalArea | Area of the projection as viewed by an elevation view (for wall projection) or as viewed by a ground floor view (for slab projection). The exact definition and calculation rules depend on the method of measurement used. | IfcQuantityArea
NominalVolume | Volume of the projection. The exact definition and calculation rules depend on the method of measurement used. | IfcQuantityVolume

Geometry Use Definition

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.

- The PlacementRelTo relationship of IfcLocalPlacement should point to the local placement of the same element, to which the projection adds, i.e. referred to by ProjectsElement.RelatingBuildingElement.

Swept Solid Representation

The geometric representation of IfcProjectionElement is defined using the swept area solid geometry. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

- RepresentationIdentifier : 'Body'
- RepresentationType : 'SweptSolid'

The following additional constraints apply to the swept solid representation:

- Solid: IfcExtrudedAreaSolid is required.
- Profile: IfcRectangleProfileDef, IfcCircleProfileDef and IfcArbitraryClosedProfileDef shall be supported.
- Extrusion: The profile shall be extruded horizontally (i.e. perpendicular to the extrusion direction of the modified element), e.g. for wall projections, or vertically (i.e. in the extrusion direction of the projected element), e.g., for floor projections.

EXAMPLE

| 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. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

- RepresentationIdentifier : 'Body'
- RepresentationType : 'Brep'

EXPRESS specification:

ENTITY IfcProjectionElement
SUBTYPE OF ( | IfcFeatureElementAddition);
END_ENTITY;

Inheritance graph

ENTITY IfcProjectionElement;
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 IfcFeatureElement;
ENTITY IfcFeatureElementAddition;
INVERSE
ProjectsElements | : | IfcRelProjectsElement FOR RelatedFeatureElement;
ENTITY IfcProjectionElement;
END_ENTITY;