IfcGeometricSet

BACnet MVD

#### IfcGeometricSet

Natural language names

| Geometrische Gruppe
| Geometric Set

##### Semantic definitions at the entity

Entity definition

The IfcGeometricSet is used for the exchange of shape representation consisting of (2D or 3D) points, curves, and surfaces, which do not have a topological structure (such as connected face sets or shells), are not tessellated and are not solid models (such as swept solids, CSG or Brep).

> NOTE Definition from ISO/CD 10303-42:
> This entity is intended for the transfer of models when a topological structure is not available.

> NOTE Entity adapted from geometric_set defined in ISO 10303-42.

> HISTORY New entity in IFC2x.

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
1 | Elements | IfcGeometricSetSelect | S[1:?] | The geometric elements which make up the geometric set, these may be points, curves or surfaces; but are required to be of the same coordinate space dimensionality. |  | X
| Dim :=Elements[1].Dim | IfcDimensionCount |  | The space dimensionality of this class, it is identical to the first element in the set. A where rule ensures that all elements have the same dimensionality. |  | X

Formal Propositions

Rule | Description
--- | ---
ConsistentDim | All elements within a geometric set shall have the same dimensionality.

##### Inherited definitions from supertypes

Entity inheritance
Attribute inheritance

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
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

X

IfcGeometricRepresentationItem
IfcGeometricSet
1 | Elements | IfcGeometricSetSelect | S[1:?] | The geometric elements which make up the geometric set, these may be points, curves or surfaces; but are required to be of the same coordinate space dimensionality. |  | X
| Dim :=Elements[1].Dim | IfcDimensionCount |  | The space dimensionality of this class, it is identical to the first element in the set. A where rule ensures that all elements have the same dimensionality. |  | X

##### Formal representations

XML Specification
`<xs:element name="IfcGeometricSet" type="ifc:IfcGeometricSet" substitutionGroup="ifc:IfcGeometricRepresentationItem" nillable="true"/>
<xs:complexType name="IfcGeometricSet">
<xs:complexContent>
<xs:extension base="ifc:IfcGeometricRepresentationItem">
<xs:sequence>
<xs:element name="Elements">
<xs:complexType>
<xs:group ref="ifc:IfcGeometricSetSelect" maxOccurs="unbounded"/>
<xs:attribute ref="ifc:itemType" fixed="ifc:IfcGeometricSetSelect"/>
<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 IfcGeometricSet
SUPERTYPE OF(IfcGeometricCurveSet)
SUBTYPE OF (IfcGeometricRepresentationItem);
Elements : SET [1:?] OF IfcGeometricSetSelect;
DERIVE
Dim : IfcDimensionCount := Elements[1].Dim;
WHERE
ConsistentDim : SIZEOF(QUERY(Temp <* Elements |
Temp.Dim <> Elements[1].Dim))
= 0;
END_ENTITY;

EXPRESS-G diagram

`

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