IFC (IFC4X3) development Bloss Transition Segment

The Bloss transition segment is a special case of a fifht order spiral where the curvature rate of change is a cubic function and the terms are dependent on the length L measured from the inflection point. The parameter value is defined as the deflection i.e. bearing angle &Theta.

Only the cubic and quadratic terms are populated with the following values: QubicTerm = L/³√2 QuadraticTerm = L/√3

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] IfcThirdOrderPolynomialSpiral IfcThirdOrderPolynomialSpiral      LayerAssignment [0:1]      StyledByItem [0:1] 1. Position [0:1] 2. CubicTerm [1:1] 3. QuadraticTerm [0:1] 4. LinearTerm [0:1] 5. ConstantTerm [0:1] IfcCurveSegment:ParentCurve1->IfcThirdOrderPolynomialSpiral:IfcThirdOrderPolynomialSpiral0 IfcLengthMeasure_0 IfcLengthMeasure IfcThirdOrderPolynomialSpiral:QubicTerm1->IfcLengthMeasure_0:IfcLengthMeasure0 IfcLengthMeasure_1 IfcLengthMeasure IfcThirdOrderPolynomialSpiral:QuadraticTerm1->IfcLengthMeasure_1:IfcLengthMeasure0

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