IFC 4.3.2.20240809 (IFC4X3_ADD2) under development

4.2.2.2.3 Clothoid Transition Segment

A clothoid segment is based on the IfcClothoid where the value for the clothoid constant A, known as flatness or homothetic parameter of the clothoid, is specified as:

$$ A=\sqrt{LR}$$

where, L is the length measured from the inflection point; and R is the radius of the clothoid.

The following diagram shows the generic classes and relationships used when applying this concept.

G IfcCurveSegment IfcCurveSegment      LayerAssignment [0:1]      StyledByItem [0:1] 1. Transition [1:1]      UsingCurves [1:?] 2. Placement [1:1] 3. SegmentStart [1:1] 4. SegmentLength [1:1] 5. ParentCurve [1:1] IfcClothoid IfcClothoid      LayerAssignment [0:1]      StyledByItem [0:1] 1. Position [1:1] 2. ClothoidConstant [1:1] IfcCurveSegment:ParentCurve1->IfcClothoid:IfcClothoid0 IfcLengthMeasure_0 IfcLengthMeasure IfcCurveSegment:SegmentStart1->IfcLengthMeasure_0:IfcLengthMeasure0 IfcLengthMeasure_1 IfcLengthMeasure IfcCurveSegment:SegmentLength1->IfcLengthMeasure_1:IfcLengthMeasure0 IfcLengthMeasure IfcLengthMeasure IfcClothoid:ClothoidConstant1->IfcLengthMeasure:IfcLengthMeasure0
Figure 4.2.2.2.3.A

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