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 inserted into a building element (all subtypes of IfcBuildingElement) by using the IfcRelProjectsElement relationship. It is also directly liked to the spatial structure of the project (and here normally to the IfcBuildingStorey) by using the IfcRelContainsInSpatialStructure 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.
- The PlacementRelTo relationship of IfcLocalPlacement should point to the local placement of the same element, which is voided by the opening, i.e. refered to by ProjectsElement.RelatingBuildingElement.
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:
- 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
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The following interpretation of dimension parameter applies for rectangular projection:
NOTE: Rectangles are now defined centric, the placement location has to be set:
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'.