4.2.2.1.3 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
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCurveSegment.htm'>IfcCurveSegment</a>
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]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcClothoid.htm'>IfcClothoid</a>
IfcClothoid LayerAssignment
[0:1]
StyledByItem
[0:1]
1. Position
[1:1]
2. ClothoidConstant
[1:1]
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCurveSegment.htm'>IfcCurveSegment</a>:ParentCurve1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcClothoid.htm'>IfcClothoid</a>:IfcClothoid0
IfcLengthMeasure_0
IfcLengthMeasure
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCurveSegment.htm'>IfcCurveSegment</a>:SegmentStart1->IfcLengthMeasure_0:IfcLengthMeasure0
IfcLengthMeasure_1
IfcLengthMeasure
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcCurveSegment.htm'>IfcCurveSegment</a>:SegmentLength1->IfcLengthMeasure_1:IfcLengthMeasure0
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcLengthMeasure.htm'>IfcLengthMeasure</a>
IfcLengthMeasure
<a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcClothoid.htm'>IfcClothoid</a>:ClothoidConstant1-><a href='/IFC/RELEASE/IFC4x3/HTML/lexical/IfcLengthMeasure.htm'>IfcLengthMeasure</a>:IfcLengthMeasure0
Figure 4.2.2.1.3.A