8.11.3.3 IfcConversionBasedUnitWithOffset

8.11.3.3.1 Semantic definition

IfcConversionBasedUnitWithOffset is a unit which is converted from another unit by applying a conversion factor and an offset.

Example: The temperature unit Fahrenheit is based on the temperature unit Kelvin as follows:

$$f=1.8k-459.67$$

wherein k is an absolute temperature expressed in Kelvin and f is the same temperature in Fahrenheit. The following entity instances provide Fahrenheit as a unit:

IfcConversionBasedUnitWithOffset(
   IfcDimensionalExponents(0, 0, 0, 0, 1, 0, 0),
   THERMODYNAMICTEMPERATUREUNIT,
   'Fahrenheit',
   IfcMeasureWithUnit(
     IfcThermodynamicTemperatureMeasure(1/1.8),
     IfcSIUnit(THERMODYNAMICTEMPERATUREUNIT, ?, KELVIN)),
   -459.67);

8.11.3.3.2 Entity inheritance

1. • IfcNamedUnit
2. • IfcConversionBasedUnit
   • IfcContextDependentUnit
   • IfcSIUnit
3. • IfcConversionBasedUnitWithOffset

8.11.3.3.3 Attributes

#	Attribute	Type	Description
IfcNamedUnit (2)
1	Dimensions	IfcDimensionalExponents	The dimensional exponents of the SI base units by which the named unit is defined.
2	UnitType	IfcUnitEnum	The type of the unit.
IfcConversionBasedUnit (3)
3	Name	IfcLabel	The word, or group of words, by which the conversion based unit is referred to.
4	ConversionFactor	IfcMeasureWithUnit	The physical quantity from which the converted unit is derived.
	HasExternalReference	SET [0:?] OF IfcExternalReferenceRelationship FOR RelatedResourceObjects	Reference to external information, e.g. library, classification, or document information, which is associated with the conversion-based unit.
Click to show 5 hidden inherited attributes Click to hide 5 inherited attributes
IfcConversionBasedUnitWithOffset (1)
5	ConversionOffset	IfcReal	A positive or negative offset to add after the inherited ConversionFactor was applied.

8.11.3.3.4 Examples

• 

  Tessellation With Blob Texture

• 

  Tessellation With Image Texture

• 

  Tessellation With Pixel Texture

8.11.3.3.5 Formal representation

ENTITY IfcConversionBasedUnitWithOffset
 SUBTYPE OF (IfcConversionBasedUnit);
	ConversionOffset : IfcReal;
END_ENTITY;

8.11.3.3.6 References

• IfcConversionBasedUnit