IFC 4.3.0.1 (IFC4X3_TC1)

8.9.3.29 IfcCylindricalSurface

8.9.3.29.1 Semantic 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.

The inherited attributes are interpreted as

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

C = Position.Location
x = Position.P[1]
y = Position.P[2]
z = Position.P[3]
R = Radius
and the surface is parameterized as:
formula where the parametric range is -∞ < u,v < ∞ .
Figure 8.9.3.29.A

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

formula The positive direction of the normal to the surface at any point on the surface is given by
Figure 8.9.3.29.B
formula, or as unit normal by
Figure 8.9.3.29.C
formula
Figure 8.9.3.29.D

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

8.9.3.29.2 Entity inheritance

8.9.3.29.3 Attributes

# Attribute Type Description
IfcRepresentationItem (2)
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems

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.

StyledByItem SET [0:1] OF IfcStyledItem FOR Item

Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.

IfcSurface (1)
* Dim IfcDimensionCount

This attribute is formally derived.

3

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

IfcElementarySurface (1)
1 Position IfcAxis2Placement3D

The position and orientation of the surface. This attribute is used in the definition of the parameterization of the surface.

Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes
IfcCylindricalSurface (1)
2 Radius IfcPositiveLengthMeasure

The radius of the cylindrical surface.

Table 8.9.3.29.E

8.9.3.29.4 Formal representation

ENTITY IfcCylindricalSurface
 SUBTYPE OF (IfcElementarySurface);
	Radius : IfcPositiveLengthMeasure;
END_ENTITY;

8.9.3.29.5 References

8.9.3.29.6 Changelog

8.9.3.29.6.1 IFC4

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