IfcAlignmentCantSegment

Item	SPF	XML	Change	Description
IFC4x3_RC1 to IFC4x3_RC2
IfcAlignmentCantSegment			MOVED	Schema changed from IFCRAIL to IFCGEOMETRICCONSTRAINTRESOURCE.
IFC4x3_RC3 to IFC4x3_RC4
IfcAlignmentCantSegment
HorizontalLength			MODIFIED	Type changed from IfcPositiveLengthMeasure to IfcNonNegativeLengthMeasure.
PredefinedType	X	X	MODIFIED	Name changed from SmoothingLength to PredefinedType. Type changed from IfcPositiveLengthMeasure to IfcAlignmentCantSegmentTypeEnum. Instantiation changed from OPTIONAL.
PredefinedType	X		DELETED

Semantic definitions at the entity

Entity definition

An IfcAlignmentCantSegment is an individual segment along IfcAlignmentCant. The cant alignment is defined by ordered segments that connect end-to-start. The points defined in a cant alignment segment are defined in a plane with x = distance along horizontal alignment and y = height relative to projected points in vertical alignment. The following cant segment types are defined:

Bloss transition - IfcAlignmentCantSegmentTypeEnum .BLOSSCURVE.
Constant cant - IfcAlignmentCantSegmentTypeEnum .CONSTANTCANT.
Cosine transition - IfcAlignmentCantSegmentTypeEnum .COSINECURVE.
Helmert transition - IfcAlignmentCantSegmentTypeEnum .HELMERTCURVE.
Linear transition - IfcAlignmentCantSegmentTypeEnum .LINEARTRANSITION.
Sine transition - IfcAlignmentCantSegmentTypeEnum SINECURVE
Viennese Bend (R) transition - IfcAlignmentCantSegmentTypeEnum .VIENNESEBEND.

For each cant segment, the following information is provided:

the start point, defined by distance along the horizontal alignment
the length (as horizontal length along the distance along (not the curve segment length))
the start cant, given by the values of left cant and right cant, measured relatively to vertical alignment
the end cant, given by the values of left cant and right cant, measured from vertical alignment
the information of tangential continuity that can be used to check continuity of segments (e.g. invalid sudden change of cant or missing cant information if end point and starting point differ over a threshold).

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
3	StartDistAlong	IfcLengthMeasure		Distance along the horizontal alignment, measured along the IfcAlignment2DHorizontal given in the length unit of the global IfcUnitAssignment.	X
4	HorizontalLength	IfcNonNegativeLengthMeasure		Length measured as distance along the horizontal alignment of the segment.	X
5	StartCantLeft	IfcLengthMeasure		Length measured for the left cant at the beginning of the segment.	X
6	EndCantLeft	IfcLengthMeasure	?	Length measured for the left cant at the end of the segment.	X
7	StartCantRight	IfcLengthMeasure		Length measured for the right cant at the beginning of the segment.	X
8	EndCantRight	IfcLengthMeasure	?	Length measured for the right cant at the end of the segment.	X
9	PredefinedType	IfcAlignmentCantSegmentTypeEnum			X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	G
IfcAlignmentParameterSegment
1	StartTag	IfcLabel	?	Tag to annotate the start point of the alignment segment.	X
2	EndTag	IfcLabel	?	Tag to annotate the end point of the alignment segment.	X
IfcAlignmentCantSegment
3	StartDistAlong	IfcLengthMeasure		Distance along the horizontal alignment, measured along the IfcAlignment2DHorizontal given in the length unit of the global IfcUnitAssignment.	X
4	HorizontalLength	IfcNonNegativeLengthMeasure		Length measured as distance along the horizontal alignment of the segment.	X
5	StartCantLeft	IfcLengthMeasure		Length measured for the left cant at the beginning of the segment.	X
6	EndCantLeft	IfcLengthMeasure	?	Length measured for the left cant at the end of the segment.	X
7	StartCantRight	IfcLengthMeasure		Length measured for the right cant at the beginning of the segment.	X
8	EndCantRight	IfcLengthMeasure	?	Length measured for the right cant at the end of the segment.	X
9	PredefinedType	IfcAlignmentCantSegmentTypeEnum			X

Formal representations

XML Specification

 <xs:element name="IfcAlignmentCantSegment" type="ifc:IfcAlignmentCantSegment" substitutionGroup="ifc:IfcAlignmentParameterSegment" nillable="true"/>

 <xs:complexType name="IfcAlignmentCantSegment">

  <xs:complexContent>

   <xs:extension base="ifc:IfcAlignmentParameterSegment">

    <xs:attribute name="StartDistAlong" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="HorizontalLength" type="ifc:IfcNonNegativeLengthMeasure" use="optional"/>

    <xs:attribute name="StartCantLeft" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="EndCantLeft" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="StartCantRight" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="EndCantRight" type="ifc:IfcLengthMeasure" use="optional"/>

    <xs:attribute name="PredefinedType" type="ifc:IfcAlignmentCantSegmentTypeEnum" use="optional"/>

   </xs:extension>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcAlignmentCantSegment

 SUBTYPE OF (IfcAlignmentParameterSegment);

  StartDistAlong : IfcLengthMeasure;

  HorizontalLength : IfcNonNegativeLengthMeasure;

  StartCantLeft : IfcLengthMeasure;

  EndCantLeft : OPTIONAL IfcLengthMeasure;

  StartCantRight : IfcLengthMeasure;

  EndCantRight : OPTIONAL IfcLengthMeasure;

  PredefinedType : IfcAlignmentCantSegmentTypeEnum;

END_ENTITY;

 EXPRESS-G diagram