IfcSurface

Semantic definitions at the entity

Entity definition

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 surface defined in ISO 10303-42.

HISTORY New entity in IFC1.5

Informal Propositions:

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

Attribute definitions

#	Attribute	Type	Cardinality	Description	C
	Dim :=3	IfcDimensionCount	[1:1]	The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
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.	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.	X
IfcGeometricRepresentationItem
IfcSurface
	Dim :=3	IfcDimensionCount	[1:1]	The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item.	X

Formal representations

XSD Specification

 <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>

EXPRESS Specification


ENTITY IfcSurface

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

 SUBTYPE OF (IfcGeometricRepresentationItem);

 DERIVE

  Dim : IfcDimensionCount := 3;

END_ENTITY;

 EXPRESS-G diagram

	Oberfläche
	Surface
	Surface