IFC 4.3.x development

8.7.3.1 IfcAlignmentCantSegment

Change log

IFC4X3_RC3

added

8.7.3.1.1 Semantic definitions at the entity

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:

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).

8.7.3.1.1 Attributes

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

8.7.3.1.2 Entity inheritance

dot_inheritance IfcAlignmentCantSegment IfcAlignmentCantSegment IfcAlignmentParameterSegment IfcAlignmentParameterSegment IfcAlignmentCantSegment->IfcAlignmentParameterSegment IfcAlignmentHorizontalSegment IfcAlignmentHorizontalSegment IfcAlignmentHorizontalSegment->IfcAlignmentParameterSegment IfcAlignmentVerticalSegment IfcAlignmentVerticalSegment IfcAlignmentVerticalSegment->IfcAlignmentParameterSegment

8.7.3.1.3 Formal representations

ENTITY IfcAlignmentCantSegment
 SUBTYPE OF (IfcAlignmentParameterSegment);
	StartDistAlong : IfcLengthMeasure;
	HorizontalLength : IfcNonNegativeLengthMeasure;
	StartCantLeft : IfcLengthMeasure;
	EndCantLeft : OPTIONAL IfcLengthMeasure;
	StartCantRight : IfcLengthMeasure;
	EndCantRight : OPTIONAL IfcLengthMeasure;
	PredefinedType : IfcAlignmentCantSegmentTypeEnum;
END_ENTITY;