IFC 4.3.2.20240128 (IFC4X3_ADD2) under development

4.1.7.1.1.1 Alignment Geometry - Horizontal

This concept template applies to alignments defined only by an horizontal layout.

  • RepresentationIdentifier = 'Axis'
  • RepresentationType = 'Curve2D'

When defining the list of segments for the business logic (i.e., IfcAlignmentHorizontalSegment, IfcAlignmentVerticalSegment, IfcAlignmentCantSegment):

  1. A zero-length segment shall be added, at the end of the list of segments for IfcAlignmentSegment.DesignParameters.
  2. If the geometry definition is also present, then each of the zero-length segments shall have a IfcCurveSegment counterpart - of length zero.

The following diagram shows the generic classes and relationships used when applying this concept. In addition, concepts may have particular importance to common or standardised industry practices and scenarios. For these specific usage scenarios, the table below shows a recommended list of general usage patterns that users may adopt.

G IfcAlignment IfcAlignment 1. GlobalId [1:1] 2. OwnerHistory [0:1] 3. Name [0:1] 4. Description [0:1]      HasAssignments [0:?]      Nests [0:1]      IsNestedBy [0:?]      HasContext [0:1]      IsDecomposedBy [0:?]      Decomposes [0:1]      HasAssociations [0:?] 5. ObjectType [0:1]      IsDeclaredBy [0:1]      Declares [0:?]      IsTypedBy [0:1]      IsDefinedBy [0:?] 6. ObjectPlacement [0:1] 7. Representation [0:1]      ReferencedBy [0:?]      PositionedRelativeTo [0:?]      ReferencedInStructures [0:?]      ContainedInStructure [0:1]      Positions [0:?] 8. PredefinedType [0:1] IfcProductDefinitionShape IfcProductDefinitionShape 1. Name [0:1] 2. Description [0:1] 3. Representations [1:?]      ShapeOfProduct [1:?]      HasShapeAspects [0:?] IfcAlignment:Representation1->IfcProductDefinitionShape:IfcProductDefinitionShape0 IfcShapeRepresentation_0 IfcShapeRepresentation 1. ContextOfItems [1:1] 2. RepresentationIdentifier [0:1] 3. RepresentationType [0:1] 4. Items [1:?]      RepresentationMap [0:1]      LayerAssignments [0:?]      OfProductRepresentation [0:?]      OfShapeAspect [0:1] IfcProductDefinitionShape:Representations1->IfcShapeRepresentation_0:IfcShapeRepresentation0 IfcLabel_2 IfcLabel IfcShapeRepresentation_0:RepresentationIdentifier1->IfcLabel_2:IfcLabel0 IfcLabel_3 IfcLabel IfcShapeRepresentation_0:RepresentationType1->IfcLabel_3:IfcLabel0 IfcCompositeCurve IfcCompositeCurve      LayerAssignment [0:1]      StyledByItem [0:1] 1. Segments [1:?] 2. SelfIntersect [1:1] IfcShapeRepresentation_0:Items1->IfcCompositeCurve:IfcCompositeCurve0 constraint_2 ='Axis' IfcLabel_2->constraint_2 constraint_3 ='Curve2D' IfcLabel_3->constraint_3 IfcCurveSegment_0 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] IfcCompositeCurve:Segments1->IfcCurveSegment_0:IfcCurveSegment0
Figure 4.1.7.1.1.1.A

General Usage

ApplicableEntity
IfcAlignment
Table 4.1.7.1.1.1.B

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