Oberfläche | |

Surface | |

Surface |

An IfcSurface is a 2-dimensional representation item positioned in 3-dimensional space. 2-dimensional means that each point at the surface can be defined by a 2-dimensional coordinate system, usually by u and v coordinates.

NOTE Definition according to ISO/CD 10303-42:1992

A surface can be envisioned as a set of connected points in 3-dimensional space which is always locally 2-dimensional, but need not be a manifold.

Each surface has a parametric representation of the form

where u and v are independent dimensionless parameters. The unit normal N, at any point on the surface, is given by the equation

NOTE Entity adapted fromsurfacedefined in ISO 10303-42.

HISTORY New entity in IFC1.5

Informal Propositions:

- A surface has non zero area.
- A surface is arcwise connected.

# | Attribute | Type | Cardinality | Description | G |
---|---|---|---|---|---|

Dim :=3 | IfcDimensionCount | The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item.
IFC4 CHANGE Derived attribute promoted from subtypes. |
X |

# | Attribute | Type | Cardinality | Description | G |
---|---|---|---|---|---|

IfcRepresentationItem | |||||

LayerAssignment | IfcPresentationLayerAssignment @AssignedItems | S[0:1] | Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.
IFC2x3 CHANGE The inverse attribute IFC4 CHANGE The inverse attribute | X | |

StyledByItem | IfcStyledItem @Item | S[0:1] | Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.
IFC2x3 CHANGE The inverse attribute | X | |

IfcGeometricRepresentationItem | |||||

IfcSurface | |||||

Dim :=3 | IfcDimensionCount | The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item.
IFC4 CHANGE Derived attribute promoted from subtypes. |
X |

` <xs:element name="IfcSurface" type="ifc:IfcSurface" abstract="true" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>`

<xs:complexType name="IfcSurface" abstract="true">

<xs:complexContent>

<xs:extension base="ifc:IfcGeometricRepresentationItem"/>

</xs:complexContent>

</xs:complexType>

```
ENTITY IfcSurface
```

ABSTRACT SUPERTYPE OF(ONEOF(IfcBoundedSurface, IfcElementarySurface, IfcSweptSurface))

SUBTYPE OF (IfcGeometricRepresentationItem)**;**

DERIVE

Dim : IfcDimensionCount := 3;

END_ENTITY;

References: IfcSurfaceOrFaceSurface IfcHalfSpaceSolid IfcSurfaceCurveSweptAreaSolid IfcGeometricSetSelect IfcCompositeCurveOnSurface IfcCurveBoundedSurface IfcPcurve IfcPointOnSurface IfcRectangularTrimmedSurface IfcSurfaceCurve IfcFaceSurface