IFC 4.3.2.20240423 (IFC4X3_ADD2) under development

4.1.7.1.1.4 Alignment Geometry - Segments

This concept template applies to segments of all type of alignment layout: IfcAlignmentHorizontalSegment, IfcAlignmentVerticalSegment and IfcAlignmentCantSegment.

  • RepresentationIdentifier = 'Axis'
  • RepresentationType = 'Segment'

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 IfcAlignmentSegment IfcAlignmentSegment 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:?] 8. DesignParameters [1:1] IfcProductDefinitionShape IfcProductDefinitionShape 1. Name [0:1] 2. Description [0:1] 3. Representations [1:?]      ShapeOfProduct [1:?]      HasShapeAspects [0:?] IfcAlignmentSegment:Representation1->IfcProductDefinitionShape:IfcProductDefinitionShape0 IfcAlignmentHorizontalSegment IfcAlignmentHorizontalSegment 1. StartTag [0:1] 2. EndTag [0:1] 3. StartPoint [1:1] 4. StartDirection [1:1] 5. StartRadiusOfCurvature [1:1] 6. EndRadiusOfCurvature [1:1] 7. SegmentLength [1:1] 8. GravityCenterLineHeight [0:1] 9. PredefinedType [1:1] IfcAlignmentSegment:DesignParameters1->IfcAlignmentHorizontalSegment:IfcAlignmentHorizontalSegment0 IfcAlignmentVerticalSegment IfcAlignmentVerticalSegment 1. StartTag [0:1] 2. EndTag [0:1] 3. StartDistAlong [1:1] 4. HorizontalLength [1:1] 5. StartHeight [1:1] 6. StartGradient [1:1] 7. EndGradient [1:1] 8. RadiusOfCurvature [0:1] 9. PredefinedType [1:1] IfcAlignmentSegment:DesignParameters1->IfcAlignmentVerticalSegment:IfcAlignmentVerticalSegment0 IfcAlignmentCantSegment IfcAlignmentCantSegment 1. StartTag [0:1] 2. EndTag [0:1] 3. StartDistAlong [1:1] 4. HorizontalLength [1:1] 5. StartCantLeft [1:1] 6. EndCantLeft [0:1] 7. StartCantRight [1:1] 8. EndCantRight [0:1] 9. PredefinedType [1:1] IfcAlignmentSegment:DesignParameters1->IfcAlignmentCantSegment:IfcAlignmentCantSegment0 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 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] IfcShapeRepresentation_0:Items1->IfcCurveSegment:IfcCurveSegment0 constraint_2 ='Axis' IfcLabel_2->constraint_2 constraint_3 ='Segment' IfcLabel_3->constraint_3
Figure 4.1.7.1.1.4.A

General Usage

ApplicableEntity
IfcAlignmentSegment
Table 4.1.7.1.1.4.B

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