IfcShellBasedSurfaceModel

Semantic definitions at the entity

Entity definition

An IfcShellBasedSurfaceModel represents the shape by a set of open or closed shells. The connected faces within the shell have a dimensionality 2 and are placed in a coordinate space of dimensionality 3.

NOTE Definition according to ISO/CD 10303-42:1992
A shell based surface model is described by a set of open or closed shells of dimensionality 2. The shells shall not intersect except at edges and vertices. In particular, distinct faces may not intersect. A complete face of one shell may be shared with another shell. Coincident portions of shells shall both reference the same faces, edges and vertices defining the coincident region. There shall be at least one shell. A shell may exist independently of a surface model.

NOTE Entity adapted from shell_based_surface_model defined in ISO 10303-42.

HISTORY New entity in IFC2x.

Informal Propositions:

The dimensionality of the shell based surface model is 2.
The shells shall not overlap or intersect except at common faces, edges or vertices.

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
1	SbsmBoundary	IfcShell	S[1:?]		X
	Dim :=3	IfcDimensionCount		The space dimensionality of this class, it is always 3.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	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 LayerAssignments has been added. IFC4 CHANGE The inverse attribute LayerAssignment has been restricted to max 1. Upward compatibility for file based exchange is guaranteed.	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 StyledByItem has been added.	X
IfcGeometricRepresentationItem
IfcShellBasedSurfaceModel
1	SbsmBoundary	IfcShell	S[1:?]		X
	Dim :=3	IfcDimensionCount		The space dimensionality of this class, it is always 3.	X

Formal representations

XML Specification

 <xs:element name="IfcShellBasedSurfaceModel" type="ifc:IfcShellBasedSurfaceModel" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>

 <xs:complexType name="IfcShellBasedSurfaceModel">

  <xs:complexContent>

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

    <xs:sequence>

     <xs:element name="SbsmBoundary">

      <xs:complexType>

       <xs:group ref="ifc:IfcShell" maxOccurs="unbounded"/>

       <xs:attribute ref="ifc:itemType" fixed="ifc:IfcShell"/>

       <xs:attribute ref="ifc:cType" fixed="set"/>

       <xs:attribute ref="ifc:arraySize" use="optional"/>

      </xs:complexType>

     </xs:element>

    </xs:sequence>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcShellBasedSurfaceModel

 SUBTYPE OF (IfcGeometricRepresentationItem);

  SbsmBoundary : SET [1:?] OF IfcShell;

 DERIVE

  Dim : IfcDimensionCount := 3;

END_ENTITY;

 EXPRESS-G diagram

	Flächenmodell (basierend auf Hüllen)
	Shell Based Surface Model