# 8.9.3.63 IfcSegmentedReferenceCurve

## 8.9.3.63.1 Semantic definition

The IfcSegmentedReferenceCurve is a curve defined in the linear parameter space of its base curve that is set in the attribute BaseCurve. The base curve provides a basis for the positioning of the collection of IfcCurveSegment occurrences. A deviating explicit position of a curve segment (IfcCurveSegment.Placement) from the axis of the base curve produces a superelevation i.e. depression or elevation from the axis of the base curve. The superelevation rate of change is directly proportionate to the curve segment parent curve curvature gradient equation (IfcCurveSegment.ParentCurve) in the linear parameter space of the base curve. If no deviation in the position of the curve segment to the base curve axis is specified, the axes (Axis and RefDirection) directions of IfcAxis2Placement are interpolated between the initial curve segment placement and the placement of the subsequent curve segment.

The parametrization of IfcSegmentReferenceCurve is based on the parametrization of BaseCurve and is not altered by the Segments.

Figure 8.9.3.63.A shows a cross section of a IfcSegmentedReferenceCurve usage for an alignmnent representation featuring cant

## 8.9.3.63.4 Formal representation

ENTITY IfcSegmentedReferenceCurve
SUBTYPE OF (IfcCompositeCurve);
BaseCurve : IfcBoundedCurve;
EndPoint : OPTIONAL IfcPlacement;
END_ENTITY;