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:
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
The positive direction of the normal to the surface at any point on the surface is given byFigure 8.9.3.29.B, or as unit normal byFigure 8.9.3.29.CFigure 8.9.3.29.D
The direction of the normal is away from the axis of the cylinder.
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.
Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.
where the parametric range is -∞ < u,v < ∞ .
The positive direction of the normal to the surface at any point on the surface is given by
, or as unit normal by
