#### 8.6.3.9 IfcGeometricSet

| Geometrische Gruppe

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.

XSD 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;

Attribute Definitions:

Elements | : | 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.
Dim | : | 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.

Formal Propositions:

ConsistentDim | : | All elements within a geometric set shall have the same dimensionality.

Inheritance Graph:

ENTITY IfcGeometricSet

| ENTITY IfcRepresentationItem

| INVERSE

LayerAssignment | : | SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems;
StyledByItem | : | SET [0:1] OF IfcStyledItem FOR Item;

| ENTITY IfcGeometricRepresentationItem

| ENTITY IfcGeometricSet

Elements | : | SET [1:?] OF IfcGeometricSetSelect;

| DERIVE

Dim | : | IfcDimensionCount := Elements[1].Dim;

END_ENTITY;

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