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8.9.3.67 IfcSurface

RV ⓘ
AbV ⓘ

ABSTRACT This definition may not be instantiated

8.9.3.67.1 Semantic 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.

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. Entity adapted from surface defined in ISO 10303-42. New entity in IFC1.5

Informal Propositions

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

8.9.3.67.2 Entity inheritance

8.9.3.67.3 Attributes

# Attribute Type Description
IfcRepresentationItem (2)
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.

The inverse attribute LayerAssignments has been added. 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.

The inverse attribute StyledByItem has been added.
Click to show 2 hidden inherited attributes Click to hide 2 inherited attributes
IfcSurface (1)
* Dim IfcDimensionCount

This attribute is formally derived. 

3

The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item.

Derived attribute promoted from subtypes.
Table 8.9.3.67.A

8.9.3.67.4 Formal representation 

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

8.9.3.67.5 References

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