8.9.3.70 IfcSurfaceOfRevolution

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. Entity adapted from surface_of_revolution defined in ISO 10303-42. New entity in IFC2x.

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.
Figure 8.9.3.70.A

Informal Propositions

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

8.9.3.70.2 Entity inheritance

8.9.3.70.3 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. 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.
	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. IFC2x3-CHANGE The inverse attribute StyledByItem has been added.
IfcSurface (1)
*	Dim	IfcDimensionCount	This attribute is formally derived. `3` The space dimensionality of IfcSurface. It is always a three-dimensional geometric representation item. IFC4-CHANGE Derived attribute promoted from subtypes.
IfcSweptSurface (2)
1	SweptCurve	IfcProfileDef	The curve to be swept in defining the surface. The curve is defined as a profile within the position coordinate system.
2	Position	OPTIONAL 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.
Click to show 5 hidden inherited attributes Click to hide 5 inherited attributes
IfcSurfaceOfRevolution (2)
3	AxisPosition	IfcAxis1Placement	A point on the axis of revolution and the direction of the axis of revolution.
*	AxisLine	IfcLine	This attribute is formally derived. `IfcRepresentationItem() \|\| IfcGeometricRepresentationItem () \|\| IfcCurve() \|\| IfcLine(AxisPosition.Location, IfcRepresentationItem() \|\| IfcGeometricRepresentationItem () \|\| IfcVector(AxisPosition.Z,1.0))` The line coinciding with the axis of revolution.

Table 8.9.3.70.B

8.9.3.70.4 Formal representation

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;

8.9.3.70.5 References

IfcSweptSurface