#### 8.16.3.8 IfcShapeRepresentation

| Représentation de forme
| Form - Repräsentation

The IfcShapeRepresentation represents the concept of a particular geometric representation of a product or a product component within a specific geometric representation context. The inherited attribute RepresentationType is used to define the geometric model used for the shape representation (e.g. 'SweptSolid', or 'Brep'), the inherited attribute RepresentationIdentifier is used to denote the kind of the representation captured by the IfcShapeRepresentation (e.g. 'Axis', 'Body', etc.).

Several representation identifiers for shape representation are included as predefined values for RepresentationIdentifier. Table 188 indicates the defined list of values for RepresentationIdentifier.

Identifier |
--- | ---
Box | Bounding box as simplified 3D box geometry of an element
Annotation | 2D annotations not representing elements
Axis | 2D or 3D Axis, or single line, representation of an element
FootPrint | 2D Foot print, or double line, representation of an element, projected to ground view
Profile | 3D line representation of a profile being planar, e.g. used for door and window outlines
Surface | 3D Surface representation, e.g. of an analytical surface, of an elementplane)
Body | 3D Body representation, e.g. as wireframe, surface, or solid model, of an element
Body-FallBack | 3D Body representation, e.g. as tessellation, or other surface, or boundary representation, added in addition to the solid model (potentially involving Boolean operations) of an element
Clearance | 3D clearance volume of the element. Such clearance region indicates space that should not intersect with the 'Body' representation of other elements, though may intersect with the 'Clearance' representation of other elements.
Lighting | Representation of emitting light as a light source within a shape representation
Table 188 — Representation identifiers

Several representation types for shape representation are included as predefined values for RepresentationType. Table 189 indicates the defined list of values for RepresentationType.

Type |
--- | ---
Point | 2 or 3 dimensional point(s)
PointCloud | 3 dimensional points prepresented by a point list
Curve | 2 or 3 dimensional curve(s)
Curve2D | 2 dimensional curve(s)
Curve3D | 3 dimensional curve(s)
Surface | 2 or 3 dimensional surface(s)
Surface2D | 2 dimensional surface(s) (a region on ground view)
Surface3D | 3 dimensional surface(s)
FillArea | 2D region(s) represented as a filled area (hatching)
Text | text defined as text literals
AdvancedSurface | 3 dimensional b-spline surface(s)
GeometricSet | points, curves, surfaces (2 or 3 dimensional)
| GeometricCurveSet | points, curves (2 or 3 dimensional)
| Annotation2D | points, curves (2 or 3 dimensional), hatches and text (2 dimensional)
SurfaceModel | face based and shell based surface model(s), or tessellated surface model(s)
| Tessellation | tessellated surface representation(s) only
SolidModel | including swept solid, Boolean results and Brep bodies; more specific types are:
| SweptSolid | swept area solids, by extrusion and revolution, excluding tapered sweeps
| AdvancedSweptSolid | swept area solids created by sweeping a profile along a directrix, and tapered sweeps
| Brep | faceted Brep's with and without voids
| AdvancedBrep | Brep's based on advanced faces, with b-spline surface geometry, with and without voids
| CSG | Boolean results of operations between solid models, half spaces and Boolean results
| Clipping | Boolean differences between swept area solids, half spaces and Boolean results
additional types | some additional representation types are provided:
| BoundingBox | simplistic 3D representation by a bounding box
| SectionedSpine | cross section based representation of a spine curve and planar cross sections. It can represent a surface or a solid and the interpolations of the between the cross sections is not defined
| LightSource | light source with (depending on type) position, orientation, light colour, intensity and attenuation
| MappedRepresentation | representation based on mapped item(s), referring to a representation map. Note: it can be seen as an inserted block reference. The shape representation of the mapped item has a representation type declaring the type of its representation items.
Table 189 — Representation types

> NOTE The definition relates to shape_representation defined in ISO 10303-41.

> HISTORY New entity in IFC1.5.

> IFC4 CHANGE The RepresentationType's 'Point', 'PointCloud', 'Curve', 'Curve3D', 'Surface', 'Surface2D', 'Surface3D', 'FillArea', 'Text', 'Tessellation', 'AdvancedBrep', 'LightSource', and the RepresentationIdentifier 'Body-FallBack', 'Profile', 'Clearance', 'Lighting' have been added.

XSD Specification:

<xs:element name="IfcShapeRepresentation" type="ifc:IfcShapeRepresentation" substitutionGroup="ifc:IfcShapeModel" nillable="true"/>
<xs:complexType name="IfcShapeRepresentation">
<xs:complexContent>
<xs:extension base="ifc:IfcShapeModel"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcShapeRepresentation

| SUBTYPE OF (IfcShapeModel);

| WHERE

WR21 | : | 'IFCREPRESENTATIONRESOURCE.IFCGEOMETRICREPRESENTATIONCONTEXT' IN TYPEOF(SELF\IfcRepresentation.ContextOfItems);
WR22 | : | SIZEOF(QUERY(temp <* Items | ('IFCTOPOLOGYRESOURCE.IFCTOPOLOGICALREPRESENTATIONITEM' IN TYPEOF(temp)) AND (NOT(SIZEOF( ['IFCTOPOLOGYRESOURCE.IFCVERTEXPOINT', 'IFCTOPOLOGYRESOURCE.IFCEDGECURVE', 'IFCTOPOLOGYRESOURCE.IFCFACESURFACE'] * TYPEOF(temp)) = 1)) )) = 0;
WR23 | : | EXISTS(SELF\IfcRepresentation.RepresentationType);
WR24 | : | IfcShapeRepresentationTypes(SELF\IfcRepresentation.RepresentationType, SELF\IfcRepresentation.Items);

END_ENTITY;

Formal Propositions:

WR21 | : | The context to which the IfcShapeRepresentation is assign, shall be of type IfcGeometricRepresentationContext.
WR22 | : | No topological representation item shall be directly used for shape representations, with the exception of IfcVertexPoint, IfcEdgeCurve, IfcFaceSurface.
WR23 | : | A representation type should be given to the shape representation.
WR24 | : | Checks the proper use of Items according to the RepresentationType.

Inheritance Graph:

ENTITY IfcShapeRepresentation

| ENTITY IfcRepresentation

ContextOfItems | : | IfcRepresentationContext;
RepresentationIdentifier | : | OPTIONAL IfcLabel;
RepresentationType | : | OPTIONAL IfcLabel;
Items | : | SET [1:?] OF IfcRepresentationItem;

| INVERSE

RepresentationMap | : | SET [0:1] OF IfcRepresentationMap FOR MappedRepresentation;
LayerAssignments | : | SET OF IfcPresentationLayerAssignment FOR AssignedItems;
OfProductRepresentation | : | SET OF IfcProductRepresentation FOR Representations;

| ENTITY IfcShapeModel

| INVERSE

| ENTITY IfcShapeRepresentation

END_ENTITY;

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