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8.9.3.64 IfcSineSpiral

AbV ⓘ

8.9.3.64.1 Semantic definition

IfcSineSpiral is a type of spiral curve for which the curvature change is dependent on the sine function.

The sine spiral curve is parameterized by its curve length and for a given parameter \(s\), the heading angle \(\theta(s)\) and the curvature \(\kappa(s)\) are defined as follows. Here, \(A_0\) corresponds to the ConstantTerm, \(A_1\) to the LinearTerm, and \(A_2\) to the SineTerm.

Heading Angle:

The Heading Angle \(\theta(s)\) represents the orientation of the tangent to the curve at a given arc length. It indicates the direction in which the curve is "pointing" at that point. By following changes in \(\theta(s)\) along the curve, one can understand how the curve rotates and changes direction as it progresses.

$$\theta(s) = \frac{1}{A_0} s \;+\; \frac{1}{2}\left(\frac{A_1}{|A_1|}\right)\left(\frac{s}{|A_1|}\right)^2\;-\; \frac{L}{2\pi A_2}\biggl(\cos\bigl(\frac{2\pi}{L}s\bigr)-1\biggr)$$

Curvature:

The Curvature \(\kappa(s)\) describes how quickly the heading angle changes with respect to the arc length. In other words, curvature indicates how "tight" a curve is turning at any point. A larger curvature corresponds to a sharper bend, while a smaller curvature corresponds to a straighter segment of the curve.

$$ \kappa(s) = \frac{L}{A_0} \;+\; \frac{A_1}{|A_1|}\left(\frac{L}{|A_1|}\right)^2 \frac{s}{L} \;+\; \frac{L}{A_2}\sin\left(\frac{2\pi}{L}s\right) $$

8.9.3.64.2 Entity inheritance

8.9.3.64.3 Attributes

# Attribute Type Description
IfcRepresentationItem (2)
LayerAssignment SET [0:1] OF IfcPresentationLayerAssignment FOR AssignedItems

Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items.

StyledByItem SET [0:1] OF IfcStyledItem FOR Item

Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve.

IfcCurve (1)
* Dim IfcDimensionCount

This attribute is formally derived.

IfcCurveDim(SELF)

The space dimensionality of this abstract class, defined differently for all subtypes, i.e. for IfcLine, IfcConic and IfcBoundedCurve.

IfcSpiral (1)
1 Position IfcAxis2Placement

No description available.

Click to show 4 hidden inherited attributes Click to hide 4 inherited attributes
IfcSineSpiral (3)
2 SineTerm IfcLengthMeasure

No description available.

3 LinearTerm OPTIONAL IfcLengthMeasure

No description available.

4 ConstantTerm OPTIONAL IfcLengthMeasure

No description available.

Table 8.9.3.64.A

8.9.3.64.4 Formal representation

ENTITY IfcSineSpiral
 SUBTYPE OF (IfcSpiral);
	SineTerm : IfcLengthMeasure;
	LinearTerm : OPTIONAL IfcLengthMeasure;
	ConstantTerm : OPTIONAL IfcLengthMeasure;
END_ENTITY;

8.9.3.64.5 References

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8.9.3.64.6 Changelog

8.9.3.64.6.1 IFC4.3_DEV_738df036

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