4.8.1.13 Reference Geometry
A specific form of geometry representation is the 'Reference' geometry. It is used to provide a geometry used for various forms of assessments (like for quantities, etc.) but not for display and also not for implicit Boolean operations in a voiding relationship.
EXAMPLE An example is the use of 'Reference' representation is for opening elements that shall not be used to create a void using the IfcRelVoidsElement
The following diagram shows the generic classes and relationships used when applying this concept.
In addition, concepts may have particular importance to common or standardised industry practices and scenarios. For these specific usage scenarios, the tables below shows a recommended list of general usage patterns that users may adopt.
G
<a href="IfcProduct.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcProduct.htm">IfcProduct</a>
IfcProduct GlobalId
[1:1]
OwnerHistory
[0:1]
Name
[0:1]
Description
[0:1]
HasAssignments
[0:?]
Nests
[0:1]
IsNestedBy
[0:?]
HasContext
[0:1]
IsDecomposedBy
[0:?]
Decomposes
[0:1]
HasAssociations
[0:?]
ObjectType
[0:1]
IsDeclaredBy
[0:1]
Declares
[0:?]
IsTypedBy
[0:1]
IsDefinedBy
[0:?]
ObjectPlacement
[0:1]
Representation
[0:1]
ReferencedBy
[0:?]
PositionedRelativeTo
[0:?]
ReferencedInStructures
[0:?]
<a href="IfcProductDefinitionShape.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcProductDefinitionShape.htm">IfcProductDefinitionShape</a>
IfcProductDefinitionShape Name
[0:1]
Description
[0:1]
Representations
[1:?]
ShapeOfProduct
[1:?]
HasShapeAspects
[0:?]
<a href="IfcProduct.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcProduct.htm">IfcProduct</a>:Representation1-><a href="IfcProductDefinitionShape.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcProductDefinitionShape.htm">IfcProductDefinitionShape</a>:IfcProductDefinitionShape0
<a href="IfcShapeRepresentation.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcShapeRepresentation.htm">IfcShapeRepresentation</a>
IfcShapeRepresentation ContextOfItems
[1:1]
Identifier
RepresentationIdentifier
[0:1]
Type
RepresentationType
[0:1]
Items
[1:?]
RepresentationMap
[0:1]
LayerAssignments
[0:?]
OfProductRepresentation
[0:?]
OfShapeAspect
[0:1]
<a href="IfcProductDefinitionShape.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcProductDefinitionShape.htm">IfcProductDefinitionShape</a>:Representations1-><a href="IfcShapeRepresentation.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcShapeRepresentation.htm">IfcShapeRepresentation</a>:IfcShapeRepresentation0
<a href="IfcGeometricRepresentationContext.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcGeometricRepresentationContext.htm">IfcGeometricRepresentationContext</a>
IfcGeometricRepresentationContext ContextIdentifier
[0:1]
ContextType
[0:1]
RepresentationsInContext
[0:?]
CoordinateSpaceDimension
[1:1]
Precision
[0:1]
WorldCoordinateSystem
[1:1]
TrueNorth
[0:1]
HasSubContexts
[0:?]
HasCoordinateOperation
[0:1]
<a href="IfcShapeRepresentation.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcShapeRepresentation.htm">IfcShapeRepresentation</a>:ContextOfItems1-><a href="IfcGeometricRepresentationContext.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcGeometricRepresentationContext.htm">IfcGeometricRepresentationContext</a>:IfcGeometricRepresentationContext0
IfcLabel_0
IfcLabel
<a href="IfcShapeRepresentation.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcShapeRepresentation.htm">IfcShapeRepresentation</a>:RepresentationIdentifier1->IfcLabel_0:IfcLabel0
IfcLabel_1
IfcLabel
<a href="IfcShapeRepresentation.htm" tppabs="https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/lexical/IfcShapeRepresentation.htm">IfcShapeRepresentation</a>:RepresentationType1->IfcLabel_1:IfcLabel0
constraint_0
=Reference
IfcLabel_0->constraint_0
Figure 4.8.1.13.A Table 4.8.1.13.B