IfcCylindricalSurface

BACnet MVD

#### IfcCylindricalSurface

Natural language names

| Zylindrische Fläche
| Cylindrical Surface
| Surface cylindrique

Change log

Item | SPF | XML | Change | Description
--- | --- | --- | --- | ---
IFC2x3 to IFC4
IfcCylindricalSurface |  |  | ADDED |

##### Semantic definitions at the entity

Entity definition

The cylindrical surface is a surface unbounded in the direction of z. Bounded cylindrical surfaces are defined by using a subtype of IfcBoundedSurface with BasisSurface being a cylindrical surface.

> NOTE 1 A bounded cylindrical surface can be defined by an IfcRectangularTrimmedSurface with BasisSurface being the cylindrical surface and U1 = 0°, U2 = 360° and V1 = lower bound in z, V2 = upper bound in z (if the plane angle measure is degree). A bounded cylindrical arc surface is provided with |U1 - U2| < 360° (assuming the Usense and Vsense agree to the sense of the basis surface).

> NOTE 2 A non-rectangular bounded cylindrical surface, e.g. the surface of a round wall underneath a sloped roof, cab be defined by an IfcCurveBoundedSurface with IfcBoundaryCurve's, being a collection of p-curve segments. A p-curve is curve which lies on the basis of a surface and is defined in the parameter space of that surface.

The inherited attributes are interpreted as

- SELF\IfcElementarySurface.Position defines the location and orientation of the cylindrical surface.
- SELF\IfcElementarySurface.Position.Location definesd a point on the axis of the cylindrical surface.
- SELF\IfcElementarySurface.Position.P[3] defines the direction of the axis of the cylindrical surface.

> NOTE Definition according to ISO/CD 10303-42:1992
> A cylindrical surface is a surface at a constant distance (the radius) from a straight line. A cylindrical surface is defined by its radius and its orientation and location. The data is to be interpreted as follows:

> >     C = Position.Location
> >     x = Position.P[1]
> >     y = Position.P[2]
> >     z = Position.P[3]
> >     R = Radius

> and the surface is parameterized as:

> where the parametric range is -∞ < u,v < ∞ .

> In the above parameterization the length unit for the unit vectors z is equal to that of the radius R. In the placement coordinate system defined above, the surface is represented by the equation S = 0, where

> The positive direction of the normal to the surface at any point on the surface is given by

> > , or as unit normal by

> The direction of the normal is away from the axis of the cylinder.

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

> HISTORY New entity in IFC4.

Attribute definitions

# | Attribute | Type | Cardinality | Description | B
--- | --- | --- | --- | --- | ---
2 | Radius | IfcPositiveLengthMeasure |  | The radius of the cylindrical surface. | 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

IfcElementarySurface
1 | Position | IfcAxis2Placement3D |  | The position and orientation of the surface. This attribute is used in the definition of the parameterization of the surface. | X | X
IfcCylindricalSurface
2 | Radius | IfcPositiveLengthMeasure |  | The radius of the cylindrical surface. | X | X

##### Formal representations

XML Specification
`<xs:element name="IfcCylindricalSurface" type="ifc:IfcCylindricalSurface" substitutionGroup="ifc:IfcElementarySurface" nillable="true"/>
<xs:complexType name="IfcCylindricalSurface">
<xs:complexContent>
<xs:extension base="ifc:IfcElementarySurface">
<xs:attribute name="Radius" type="ifc:IfcPositiveLengthMeasure" use="optional"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
`
EXPRESS Specification
`ENTITY IfcCylindricalSurface
SUBTYPE OF (IfcElementarySurface);
Radius : IfcPositiveLengthMeasure;
END_ENTITY;

EXPRESS-G diagram

`

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