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.NOTE Entity adapted from

surfacedefined 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 | Description |
---|---|---|---|

IfcRepresentationItem | |||

LayerAssignment | SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems | 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 LayerAssignments has been added. > IFC4 CHANGE The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed. | |

StyledByItem | SET [0:1] OF IfcStyledItem FOR Item | 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 StyledByItem has been added. | |

IfcGeometricRepresentationItem | |||

IfcSurface | |||

Dim | INVALID | The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item. > IFC4 CHANGE Derived attribute promoted from subtypes. |

ENTITY IfcSurface ABSTRACT SUPERTYPE OF (ONEOF (IfcBoundedSurface ,IfcElementarySurface ,IfcSectionedSurface ,IfcSweptSurface)) SUBTYPE OF (IfcGeometricRepresentationItem); DERIVE Dim : IfcDimensionCount := 3; END_ENTITY;