4.1.2.2.4 Cosine Spiral Transition Segment

The cosine transition segment is a special case of a spiral where the curvature rate of change is a cosine 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.

The values of its individual terms dependent on segment length L: CosineTerm = L Constant = 1

Figure 10 illustrates an instance diagram.

Cosine Spiral Transition SegmentIfcCurveSegmentIfcParameterValueIfcParameterValueIfcCosineSpiralIfcLengthMeasureIfcReal

Figure 10 — Cosine Spiral Transition Segment

mvdXML Specification
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  <Rules>
    <AttributeRule AttributeName="ParentCurve">
      <EntityRules>
        <EntityRule EntityName="IfcCosineSpiral">
          <AttributeRules>
            <AttributeRule AttributeName="CosineTerm">
              <EntityRules>
                <EntityRule EntityName="IfcLengthMeasure" />
              </EntityRules>
            </AttributeRule>
            <AttributeRule AttributeName="ConstantTerm">
              <EntityRules>
                <EntityRule EntityName="IfcReal" />
              </EntityRules>
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      </EntityRules>
    </AttributeRule>
    <AttributeRule AttributeName="SegmentStart">
      <EntityRules>
        <EntityRule EntityName="IfcParameterValue" />
      </EntityRules>
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    <AttributeRule AttributeName="SegmentLength">
      <EntityRules>
        <EntityRule EntityName="IfcParameterValue" />
      </EntityRules>
    </AttributeRule>
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