8.18.3.12 IfcRepresentation
ABSTRACT This definition may not be instantiated
8.18.3.12.1 Semantic definition
The IfcRepresentation defines the general concept of representing product properties and in particular the product shape.
Definition from ISO 10303-43: A representation is a collection of one or more representation items that are related in a specified representation context. The relationship of representation item to representation context is the basis for distinguishing which representation item entities are related. A representation item can be related to a representation context directly, when it occurs as an element is a representation, or indirectly, when it is referenced through any number of intervening entities, each of type representation item. Entity adapted from representation defined in ISO 10303-42. New entity in IFC2.0 The inverse attributes LayerAssignments and_RepresentationMap_ have been added with upward compatibility. Entity IfcRepresentation has been changed into an ABSTRACT supertype.Representation Use Definition
Each representation, either IfcShapeRepresentation, or IfcTopologyRepresentation shall have a well defined:
- ContextOfItems: Reference to an IfcGeometricRepresentationContext as agreed for this representation.
- RepresentationIdentifier: Name of the representation, for example, 'Body' for 3D shape, 'FootPrint' for 2D ground view, 'Axis' for reference axis.
- RepresentationType: Name for the geometric, or topological representation type, for example, 'SweptSolid' for 3D swept solids, 'Brep' for boundary representation.
8.18.3.12.2 Entity inheritance
8.18.3.12.3 Attributes
| # | Attribute | Type | Description |
|---|---|---|---|
| IfcRepresentation (7) | |||
| 1 | ContextOfItems | IfcRepresentationContext |
Definition of the representation context for which the different subtypes of representation are valid. |
| 2 | RepresentationIdentifier | OPTIONAL IfcLabel |
The optional identifier of the representation as used within a project. |
| 3 | RepresentationType | OPTIONAL IfcLabel |
The description of the type of a representation context. The representation type defines the type of geometry or topology used for representing the product representation. More information is given at the subtypes IfcShapeRepresentation and IfcTopologyRepresentation. The supported values for context type are to be specified by implementers agreements. |
| 4 | Items | SET [1:?] OF IfcRepresentationItem |
Set of geometric representation items that are defined for this representation. |
| RepresentationMap | SET [0:1] OF IfcRepresentationMap FOR MappedRepresentation |
Use of the representation within an IfcRepresentationMap. If used, this IfcRepresentation may be assigned to many representations as one of its Items using an IfcMappedItem. Using IfcRepresentationMap is the way to share one representation (often of type IfcShapeRepresentation) by many products. The inverse attribute LayerAssignments has been added |
|
| LayerAssignments | SET [0:?] OF IfcPresentationLayerAssignment FOR AssignedItems |
Assignment of the whole representation to a single or multiple layer(s). The LayerAssigments can be overridden by LayerAssigments of the IfcRepresentationItem's within the list of Items. Implementation agreements can restrict the maximum number of layer assignments to 1. The inverse attribute LayerAssignments has been added |
|
| OfProductRepresentation | SET [0:?] OF IfcProductRepresentation FOR Representations |
Reference to the product representations to which this individual representation applies. In most cases it is the reference to one or many product shapes, to which this shape representation is applicable. Inverse relationship cardinality relaxed to be 0:N. |
|
8.18.3.12.4 Formal representation
ENTITY IfcRepresentation
ABSTRACT SUPERTYPE OF (ONEOF
(IfcShapeModel
,IfcStyleModel));
ContextOfItems : IfcRepresentationContext;
RepresentationIdentifier : OPTIONAL IfcLabel;
RepresentationType : OPTIONAL IfcLabel;
Items : SET [1:?] OF IfcRepresentationItem;
INVERSE
RepresentationMap : SET [0:1] OF IfcRepresentationMap FOR MappedRepresentation;
LayerAssignments : SET [0:?] OF IfcPresentationLayerAssignment FOR AssignedItems;
OfProductRepresentation : SET [0:?] OF IfcProductRepresentation FOR Representations;
END_ENTITY;