IfcSurfaceOfRevolution

BACnet MVD

#### IfcSurfaceOfRevolution

Natural language names

| Oberfläche - Entlang einer Achse rotiert
| Surface Of Revolution
| Surface de révolution

Change log

Item | SPF | XML | Change | Description
--- | --- | --- | --- | ---
IFC2x3 to IFC4
IfcSurfaceOfRevolution |  |  |  |
Position |  |  | MODIFIED | Instantiation changed to OPTIONAL.

##### Semantic definitions at the entity

Entity definition

The IfcSurfaceOfRevolution is a surface derived by rotating a curve about an axis.

> NOTE Definition according to ISO/CD 10303-42:1992
> A surface of revolution is the surface obtained by rotating a curve one complete revolution about an axis. The data shall be interpreted as below.
> The parameterization is as follows where the curve has a parameterization λ(u):

> > C = AxisPosition.Location
> > V = AxisPosition.Z

> In order to produce a single-valued surface with a complete revolution, the curve shall be such that when expressed in a cylindrical coordinate system (r,φ ,z) centred at C with an axis V, no two distinct parametric points on the curve shall have the same values for (r, z). For a surface of revolution the parametric range is 0 < u < 360 degree. The parameterization range for v is defined by referenced curve.

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

> HISTORY New entity in IFC2x.

Informal Propositions:

1. The surface shall not self-intersect
2. The swept curve shall not be coincident with the axis line for any finite part of its legth.

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
3 | AxisPosition | IfcAxis1Placement |  | A point on the axis of revolution and the direction of the axis of revolution. | X | X
| AxisLine :=IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcCurve() || IfcLine(AxisPosition.Location, IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcVector(AxisPosition.Z,1.0)) | IfcLine |  | The line coinciding with the axis of revolution. | X | X

##### 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
IfcSurface

Dim
:=3

IfcDimensionCount

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

> IFC4 CHANGE Derived attribute promoted from subtypes.

X

X

IfcSweptSurface
1 | SweptCurve | IfcProfileDef |  | The curve to be swept in defining the surface. The curve is defined as a profile within the position coordinate system. | X | X

2

Position

IfcAxis2Placement3D

?

Position coordinate system for the swept surface, provided by a profile definition within the XY plane of the Position coordinates. If not provided, the position of the profile being swept is determined by the object coordinate system. In this case, the swept surface is not repositioned.

> IFC4 CHANGE The attribute has been changed to OPTIONAL with upward compatibility for file-based exchange.

X

IfcSurfaceOfRevolution
3 | AxisPosition | IfcAxis1Placement |  | A point on the axis of revolution and the direction of the axis of revolution. | X | X
| AxisLine :=IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcCurve() || IfcLine(AxisPosition.Location, IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcVector(AxisPosition.Z,1.0)) | IfcLine |  | The line coinciding with the axis of revolution. | X | X

##### Formal representations

XML Specification
`<xs:element name="IfcSurfaceOfRevolution" type="ifc:IfcSurfaceOfRevolution" substitutionGroup="ifc:IfcSweptSurface" nillable="true"/>
<xs:complexType name="IfcSurfaceOfRevolution">
<xs:complexContent>
<xs:extension base="ifc:IfcSweptSurface">
<xs:sequence>
<xs:element name="AxisPosition" type="ifc:IfcAxis1Placement" nillable="true"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcSurfaceOfRevolution
SUBTYPE OF (IfcSweptSurface);
AxisPosition : IfcAxis1Placement;
DERIVE
AxisLine : IfcLine := IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcCurve() || IfcLine(AxisPosition.Location, IfcRepresentationItem() || IfcGeometricRepresentationItem () || IfcVector(AxisPosition.Z,1.0));
END_ENTITY;

EXPRESS-G diagram

`

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