added |

A clothoid is a planar curve in the form of a spiral. This curve has the property that the curvature varies linearly with the arc length.

NOTE Definition according to ISO 10303-42:2003

Interpretation of the data shall be as follows:

`C = SELF\IfcSpiral.Position.Location x = SELF\IfcSpiral.Position.P[1] y = SELF\IfcSpiral.Position.P[2] A = ClothoidConstant`

and the clothoid is parameterized as:and the parametric range is: -∞ <

u< ∞The arc length

sof the curve, from the point C, is given by the formula:The curvature

κand radius of the curvatureρ, at any point of the curve, are related to the arc lengthsby the formulae:

NOTE Formulae adapted from

clothoiddefined in ISO 10303-42

# | Attribute | Type | Description |
---|---|---|---|

IfcRepresentationItem | |||

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. | |

IfcGeometricRepresentationItem | |||

IfcCurve | |||

Dim | INVALID | The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve. | |

IfcSpiral | |||

1 | Position | OPTIONAL IfcAxis2Placement | |

IfcClothoid | |||

2 | ClothoidConstant | IfcLengthMeasure | The constant which defines the relationship between curvature and arc length for the curve. |

ENTITY IfcClothoid SUBTYPE OF (IfcSpiral); ClothoidConstant : IfcLengthMeasure; END_ENTITY;