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IfcQuantityLength

作者:互联网

IfcQuantityLength是一个物理量,它定义了一个派生的长度度量来提供元素的物理属性。它通常由测量方法给出的特定测量规则下元素的物理性质导出。

 

示例:屋顶结构内的椽可根据其长度进行测量(考虑公共横截面)。长度的实际大小取决于所用的测量方法。

IFC2x中增加的新实体。它替换了以前IFC版本中使用的calcXxx属性。

 

Formal Propositions

RuleDescription
WR21 If a unit is given, the unit type shall be a length unit.
WR22 A valid length quantity shall be greater than or equal to zero.
 

 

 

 

 

 

 

Attribute inheritance

#AttributeTypeCardinalityDescriptionC
IfcPhysicalQuantity
1 Name IfcLabel [1:1] Name of the element quantity or measure. The name attribute has to be made recognizable by further agreements. X
2 Description IfcText [0:1] Further explanation that might be given to the quantity. X
  HasExternalReferences IfcExternalReferenceRelationship
@RelatedResourceObjects
S[0:?] Reference to an external reference, e.g. library, classification, or document information, that is associated to the quantity. X
  PartOfComplex IfcPhysicalComplexQuantity
@HasQuantities
S[0:1] Reference to a physical complex quantity in which the physical quantity may be contained. X
IfcPhysicalSimpleQuantity
3 Unit IfcNamedUnit [0:1] Optional assignment of a unit. If no unit is given, then the global unit assignment, as established at the IfcProject, applies to the quantity measures. X
IfcQuantityLength
4 LengthValue IfcLengthMeasure [1:1] Length measure value of this quantity. X
5 Formula IfcLabel [0:1] A formula by which the quantity has been calculated. It can be assigned in addition to the actual value of the quantity. Formulas could be mathematic calculations (like width x height), database links, or a combination. The formula is for informational purposes only. X
 

EXPRESS Specification

ENTITY IfcQuantityLength
 SUBTYPE OF (IfcPhysicalSimpleQuantity);
  LengthValue : IfcLengthMeasure;
  Formula : OPTIONAL IfcLabel;
 WHERE
  WR21 : NOT(EXISTS(SELF\IfcPhysicalSimpleQuantity.Unit)) OR (SELF\IfcPhysicalSimpleQuantity.Unit.UnitType = IfcUnitEnum.LENGTHUNIT);
  WR22 : LengthValue >= 0.;
END_ENTITY;

 

标签:IfcLabel,IfcPhysicalSimpleQuantity,IfcQuantityLength,LengthValue,unit,quantity
来源: https://www.cnblogs.com/herd/p/14397233.html