Class Units
Unit
instances.
Unit names and definitions in this class follow the definitions provided in the EPSG geodetic dataset
(when the unit exists in that dataset),
except “year” which has been renamed “tropical year”.
This class focuses on the most commonly used units in the geospatial domain:
angular units (degree, arcsecond, …),
linear units (kilometre, nautical mile, …) and
temporal units (day, year, …),
but some other kind of units are also provided for completeness.
The main quantities are listed below, together with some related units:
Quantity type  System unit  Some conventional units  

Fundamental:  
Length  (L)  METRE  CENTIMETRE , KILOMETRE , NAUTICAL_MILE , STATUTE_MILE , FOOT 
Mass  (M)  KILOGRAM  
Time  (T)  SECOND  MILLISECOND , MINUTE , HOUR , DAY , WEEK , TROPICAL_YEAR 
ElectricCurrent  (I)  AMPERE  
Temperature  (Θ)  KELVIN  CELSIUS , FAHRENHEIT 
AmountOfSubstance  (N)  MOLE  
LuminousIntensity  (J)  CANDELA  
Dimensionless:  
Angle  RADIAN  DEGREE , ARC_MINUTE , ARC_SECOND , GRAD  
SolidAngle  STERADIAN  
Derived:  
Area  (A)  SQUARE_METRE  HECTARE 
Volume  (V)  CUBIC_METRE  
Speed  (ν)  METRES_PER_SECOND  KILOMETRES_PER_HOUR 
Pressure  PASCAL  HECTOPASCAL , DECIBAR , BAR , ATMOSPHERE 
 Since:
 0.3
Defined in the sisutility
module

Field Summary
Modifier and TypeFieldDescriptionstatic final Unit<ElectricCurrent>
The SI base unit for electric current (A).Unit of measurement defined as 1/60 degree (1′).Unit of measurement defined as 1/(60×60) degree (1″).Unit of measurement defined as 101325 pascals (1 atm).Unit of measurement defined as 100000 pascals (1 bar).static final Unit<LuminousIntensity>
The SI base unit for luminous intensity (cd).static final Unit<Temperature>
Unit of measurement defined as the temperature in Kelvin minus 273.15.Unit of measurement defined as 0.01 metres (1 cm).Unit of measurement defined as 0.3047972654 metres.static final Unit<ElectricCharge>
The SI derived unit for electric charge (C).The SI derived unit for volume (m³).Unit of measurement defined as 24×60×60 seconds (1 d).Unit of measurement defined as 10000 pascals (1 dbar).static final Unit<Dimensionless>
Subdivision of logarithm of ratio of the measured quantity to a reference quantity (dB).Unit of measurement defined as π/180 radians (1°).static final Unit<Temperature>
Unit of measurement defined as 1.8 degree Celsius plus 32.static final Unit<ElectricCapacitance>
The SI derived unit for electric capacitance (F).Unit of measurement defined as exactly 0.3048 metres (1 ft).static final Unit<Acceleration>
Unit of measurement defined as 1/100 metres per second squared (1 cm/s²).Unit of measurement defined as π/200 radians (1 grad).A SI conventional unit for mass (g).Unit of measurement defined as 10,000 square metres (1 ha).Unit of measurement defined as 100 pascals (1 hPa).static final Unit<ElectricInductance>
The SI derived unit for inductance (H).The SI derived unit for frequency (Hz).Unit of measurement defined as 60×60 seconds (1 h).Unit of measurement defined as 2.54 centimetres (1 in).The SI derived unit for energy (J).static final Unit<Temperature>
The SI base unit for thermodynamic temperature (K).The SI base unit for mass (kg).Unit of measurement defined as 1000 metres (1 km).Unit of measurement defined as 1/3.6 metres per second (1 km/h).The unit for litre volume (L, l or ℓ).static final Unit<LuminousFlux>
The SI derived unit for luminous flux (lm).static final Unit<Illuminance>
The SI derived unit for illuminance (lx).The SI base unit for distances (m).The SI derived unit for speed (m/s).static final Unit<Acceleration>
The SI derived unit for acceleration (m/s²).Unit of measurement defined as 10^{6} radians (1 µrad).Unit of measurement defined as 0.001 metres (1 mm).Unit of measurement defined as 10^{3} seconds (1 ms).Unit of measurement defined as 60 seconds (1 min).static final Unit<AmountOfSubstance>
The SI base unit for amount of substance (mol).Unit of measurement defined as 10^{9} metres (1 nm).Unit of measurement defined as exactly 1852 metres (1 M).The SI derived unit for force (N).static final Unit<ElectricResistance>
The SI derived unit for electric resistance (Ω).The SI derived unit for pressure (Pa).static final Unit<Dimensionless>
Dimensionless unit for percentages (%).static final Unit<Dimensionless>
Dimensionless unit for pixels (px).Unit of measurement defined as 0.013837 inch (1 pt).static final Unit<Dimensionless>
Dimensionless unit for parts per million (ppm).Salinity measured using PSS78.The SI unit for plane angles (rad).static final Unit<AngularVelocity>
The unit for angular velocity (rad/s).The SI base unit for durations (s).static final Unit<ElectricConductance>
The SI derived unit for electric conductance (S).The SI derived unit for area (m²).Unit of measurement defined as exactly 1609.344 metres (1 mi).static final Unit<SolidAngle>
The SI unit for solid angles (sr).static final Unit<MagneticFluxDensity>
The SI derived unit for magnetic flux density (T).Unit of measurement approximately equals to 365.24219 days (1 a).static final Unit<Dimensionless>
The base dimensionless unit for scale measurements.Unit of measurement approximately equals to 0.3048006096… metres.static final Unit<ElectricPotential>
The SI derived unit for electric potential difference (V).The SI derived unit for power (W).static final Unit<MagneticFlux>
The SI derived unit for magnetic flux (Wb).Unit of measurement defined as 7 days (1 wk). 
Method Summary
Modifier and TypeMethodDescriptionstatic Number[]
coefficients
(UnitConverter converter) Returns the coefficients of the given converter expressed as a polynomial equation.static UnitConverter
Creates a linear converter from the given scale and offset.static double
derivative
(UnitConverter converter, double value) Returns the derivative of the given converter at the given value, orNaN
if this method cannot compute it.ensureAngular
(Unit<?> unit) Makes sure that the specified unit is either null or an angular unit.ensureLinear
(Unit<?> unit) Makes sure that the specified unit is either null or a linear unit.static Unit<Dimensionless>
ensureScale
(Unit<?> unit) Makes sure that the specified unit is either null or a scale unit.ensureTemporal
(Unit<?> unit) Makes sure that the specified unit is either null or a temporal unit.static Integer
getEpsgCode
(Unit<?> unit, boolean inAxis) Returns the EPSG code of the given units, ornull
if unknown.static boolean
isAngular
(Unit<?> unit) Returnstrue
if the given unit is a linear unit.static boolean
Returnstrue
if the given unit is a linear unit.static boolean
isPressure
(Unit<?> unit) Returnstrue
if the given unit is a pressure unit.static boolean
Returnstrue
if the given unit is a dimensionless scale unit.static boolean
isTemporal
(Unit<?> unit) Returnstrue
if the given unit is a temporal unit.Multiplies the given unit by the given ratio.static <Q extends Quantity<Q>>
doubletoStandardUnit
(Unit<Q> unit) Returns the factor by which to multiply the standard unit in order to get the given unit.static Unit<?>
Parses the given symbol.static Unit<?>
valueOfEPSG
(int code) Returns a hardcoded unit from an EPSG code.

Field Details

NANOMETRE
Unit of measurement defined as 10^{9} metres (1 nm). This unit is often used in wavelength measurements. The system unit isMETRE
and the unlocalized name is "nanometre".Related units SI units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,METRES_PER_SECOND
. Since:
 0.8
 See Also:

MILLIMETRE
Unit of measurement defined as 0.001 metres (1 mm). The system unit isMETRE
, the unlocalized name is “millimetre” and the identifier is EPSG:1025.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,METRES_PER_SECOND
. Since:
 0.8

CENTIMETRE
Unit of measurement defined as 0.01 metres (1 cm). The system unit isMETRE
, the unlocalized name is “centimetre” and the identifier is EPSG:1033.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,METRES_PER_SECOND
. Since:
 0.8

METRE
The SI base unit for distances (m). The unlocalized name is “metre” and the identifier is EPSG:9001. This is the base of all other linear units.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,METRES_PER_SECOND
. Since:
 0.8

KILOMETRE
Unit of measurement defined as 1000 metres (1 km). The system unit isMETRE
, the unlocalized name is “kilometre” and the identifier is EPSG:9036.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,KILOMETRES_PER_HOUR
. Since:
 0.8

NAUTICAL_MILE
Unit of measurement defined as exactly 1852 metres (1 M). This is approximately the distance between two parallels of latitude separated by one arcminute. The system unit isMETRE
, the unlocalized name is “nautical mile” and the identifier is EPSG:9030.There is no internationally agreed symbol for nautical mile. Apache SIS uses “M” in agreement with the International Hydrographic Organization (IHO) and the International Bureau of Weights and Measures (BIPM). But “NM” and “nmi” are also in use.
Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,KILOMETRES_PER_HOUR
. Since:
 0.8

STATUTE_MILE
Unit of measurement defined as exactly 1609.344 metres (1 mi). This unit is often named “mile” without qualifier, but Apache SIS uses “statute mile” for emphasing the difference with nautical mile. The system unit isMETRE
. The unlocalized name is “statute mile” but is localized as "international mile" in the US for avoiding confusion with the US survey mile. The identifier is EPSG:9093.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,KILOMETRES_PER_HOUR
. Since:
 0.8

US_SURVEY_FOOT
Unit of measurement approximately equals to 0.3048006096… metres. The legal definition is exactly 12/39.37 metres. The system unit isMETRE
, the unlocalized name is “US survey foot” and the identifier is EPSG:9003.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,METRES_PER_SECOND
. Since:
 0.8

CLARKE_FOOT
Unit of measurement defined as 0.3047972654 metres. The system unit isMETRE
, the unlocalized name is “Clarke’s foot” and the identifier is EPSG:9005.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,METRES_PER_SECOND
. Since:
 0.8

FOOT
Unit of measurement defined as exactly 0.3048 metres (1 ft). The system unit isMETRE
, the unlocalized name is “foot” and the identifier is EPSG:9002.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,METRES_PER_SECOND
. Since:
 0.8

INCH
Unit of measurement defined as 2.54 centimetres (1 in). The system unit isMETRE
and the unlocalized name is “inch”.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,METRES_PER_SECOND
. Since:
 0.8

POINT
Unit of measurement defined as 0.013837 inch (1 pt). This is commonly used to measure the height of a font. The system unit isMETRE
and the unlocalized name is “point”.Related units SI length units: NANOMETRE
,MILLIMETRE
,CENTIMETRE
,METRE
,KILOMETRE
.In other systems: POINT
,INCH
,FOOT
,CLARKE_FOOT
,US_SURVEY_FOOT
,STATUTE_MILE
,NAUTICAL_MILE
.Derived units: SQUARE_METRE
,CUBIC_METRE
,METRES_PER_SECOND
. Since:
 0.8

SQUARE_METRE
The SI derived unit for area (m²). The unlocalized name is “square metre”.Related units SI area units: SQUARE_METRE
,HECTARE
.Derived units: CUBIC_METRE
. Since:
 0.8

HECTARE
Unit of measurement defined as 10,000 square metres (1 ha). One hectare is exactly equals to one hectometre (1 hm²). While not an SI unit, the hectare is often used in the measurement of land. The unlocalized name is “hectare”.Related units SI area units: SQUARE_METRE
,HECTARE
.Derived units: CUBIC_METRE
. Since:
 0.8

CUBIC_METRE
The SI derived unit for volume (m³). The unlocalized name is “cubic metre”. Since:
 0.8

LITRE
The unit for litre volume (L, l or ℓ). The unlocalized name is “litre”. Since:
 0.8

STERADIAN
The SI unit for solid angles (sr). The unlocalized name is “steradian”. Since:
 0.8

MICRORADIAN
Unit of measurement defined as 10^{6} radians (1 µrad). The distance of one microradian of latitude on Earth is approximately 2 millimetres. The system unit isRADIAN
, the unlocalized name is “microradian” and the identifier is EPSG:9109.Related units SI angle units: MICRORADIAN
,RADIAN
.In other systems: DEGREE
,ARC_MINUTE
,ARC_SECOND
,GRAD
.Derived units: STERADIAN
. Since:
 0.8

RADIAN
The SI unit for plane angles (rad). There is 2π radians in a circle. The unlocalized name is “radian” and the identifier is EPSG:9101. This is the base of all other angular units.Related units SI angle units: MICRORADIAN
,RADIAN
.In other systems: DEGREE
,ARC_MINUTE
,ARC_SECOND
,GRAD
.Derived units: STERADIAN
,RADIANS_PER_SECOND
. Since:
 0.8

DEGREE
Unit of measurement defined as π/180 radians (1°). There is 360° in a circle. The system unit isRADIAN
, the unlocalized name is “degree” and the identifier is EPSG:9102.Related units SI angle units: MICRORADIAN
,RADIAN
.In other systems: DEGREE
,ARC_MINUTE
,ARC_SECOND
,GRAD
.Derived units: STERADIAN
. Since:
 0.8

ARC_MINUTE
Unit of measurement defined as 1/60 degree (1′). The distance of one arcminute of latitude on Earth is approximately 1852 metres (one nautical mile). The system unit isRADIAN
, the unlocalized name is “arcminute” and the identifier is EPSG:9103.Related units SI angle units: MICRORADIAN
,RADIAN
.In other systems: DEGREE
,ARC_MINUTE
,ARC_SECOND
,GRAD
.Derived units: STERADIAN
. Since:
 0.8

ARC_SECOND
Unit of measurement defined as 1/(60×60) degree (1″). The distance of one arcsecond of latitude on Earth is approximately 31 metres. This unit of measurement is used for rotation terms in BursaWolf parameters. The system unit isRADIAN
, the unlocalized name is “arcsecond” and the identifier is EPSG:9104.Related units SI angle units: MICRORADIAN
,RADIAN
.In other systems: DEGREE
,ARC_MINUTE
,ARC_SECOND
,GRAD
.Derived units: STERADIAN
. Since:
 0.8

GRAD
Unit of measurement defined as π/200 radians (1 grad). There is 400 grads in a circle. The system unit isRADIAN
, the unlocalized name is “grad”, but the “gon” alias is also accepted. The identifier is EPSG:9105.Related units SI angle units: MICRORADIAN
,RADIAN
.In other systems: DEGREE
,ARC_MINUTE
,ARC_SECOND
,GRAD
.Derived units: STERADIAN
. Since:
 0.8

MILLISECOND
Unit of measurement defined as 10^{3} seconds (1 ms). This unit is useful for interoperability with various methods from the standard Java library. The system unit isSECOND
and the unlocalized name is “millisecond”.Related units SI time units: MILLISECOND
,SECOND
.In other systems: MINUTE
,HOUR
,DAY
,WEEK
,TROPICAL_YEAR
.Derived units: METRES_PER_SECOND
,HERTZ
. Since:
 0.3
 See Also:

SECOND
The SI base unit for durations (s). The unlocalized name is “second” and the identifier is EPSG:1040. This is the base of all other temporal units.Related units SI time units: MILLISECOND
,SECOND
.In other systems: MINUTE
,HOUR
,DAY
,WEEK
,TROPICAL_YEAR
.Derived units: METRES_PER_SECOND
,HERTZ
. Since:
 0.8

MINUTE
Unit of measurement defined as 60 seconds (1 min). The system unit isSECOND
and the unlocalized name is “minute”.Related units SI time units: MILLISECOND
,SECOND
.In other systems: MINUTE
,HOUR
,DAY
,WEEK
,TROPICAL_YEAR
.Derived units: METRES_PER_SECOND
,HERTZ
. Since:
 0.8

HOUR
Unit of measurement defined as 60×60 seconds (1 h). The system unit isSECOND
and the unlocalized name is “hour”.Related units SI time units: MILLISECOND
,SECOND
.In other systems: MINUTE
,HOUR
,DAY
,WEEK
,TROPICAL_YEAR
.Derived units: KILOMETRES_PER_HOUR
,HERTZ
. Since:
 0.8

DAY
Unit of measurement defined as 24×60×60 seconds (1 d). The system unit isSECOND
and the unlocalized name is “day”.Related units SI time units: MILLISECOND
,SECOND
.In other systems: MINUTE
,HOUR
,DAY
,WEEK
,TROPICAL_YEAR
.Derived units: KILOMETRES_PER_HOUR
,HERTZ
. Since:
 0.8

WEEK
Unit of measurement defined as 7 days (1 wk). The system unit isSECOND
and the unlocalized name is “week”.Related units SI time units: MILLISECOND
,SECOND
.In other systems: MINUTE
,HOUR
,DAY
,WEEK
,TROPICAL_YEAR
.Derived units: KILOMETRES_PER_HOUR
,HERTZ
. Since:
 0.8

TROPICAL_YEAR
Unit of measurement approximately equals to 365.24219 days (1 a). This is defined by the International Union of Geological Sciences (IUGS) as exactly 31556925.445 seconds, taken as the length of the tropical year in the the year 2000. The system unit isSECOND
, the unlocalized name is “year” and the identifier is EPSG:1029.Related units SI time units: MILLISECOND
,SECOND
.In other systems: MINUTE
,HOUR
,DAY
,WEEK
,TROPICAL_YEAR
.Derived units: KILOMETRES_PER_HOUR
,HERTZ
. Since:
 0.8

HERTZ
The SI derived unit for frequency (Hz). One hertz is equal to one cycle per second. The unlocalized name is “hertz”.Related units Components: SECOND
^{1} Since:
 0.8

RADIANS_PER_SECOND
The unit for angular velocity (rad/s). The identifier is EPSG:1035. Since:
 0.8

METRES_PER_SECOND
The SI derived unit for speed (m/s). The unlocalized name is “metres per second” and the identifier is EPSG:1026.Related units SI speed units: METRES_PER_SECOND
.In other systems: KILOMETRES_PER_HOUR
.Components: METRE
∕SECOND
 Since:
 0.8

KILOMETRES_PER_HOUR
Unit of measurement defined as 1/3.6 metres per second (1 km/h). The system unit isMETRES_PER_SECOND
and the unlocalized name is “kilometres per hour”.Related units SI speed units: METRES_PER_SECOND
.In other systems: KILOMETRES_PER_HOUR
.Components: KILOMETRE
∕HOUR
 Since:
 0.8

METRES_PER_SECOND_SQUARED
The SI derived unit for acceleration (m/s²). The unlocalized name is “metres per second squared”.Related units SI acceleration units: METRES_PER_SECOND_SQUARED
.In other systems: GAL
.Components: METRES_PER_SECOND
∕SECOND
 Since:
 1.2

GAL
Unit of measurement defined as 1/100 metres per second squared (1 cm/s²). This is a CGS unit (not a SI unit) used in geodesy and geophysics to express acceleration due to gravity. The system unit isMETRES_PER_SECOND_SQUARED
, the symbol is "Gal" (uppercase first letter) and the unlocalized name is “gal” (lowercase letter).Related units SI acceleration units: METRES_PER_SECOND_SQUARED
.In other systems: GAL
.Components: CENTIMETRE
∕SECOND
² Since:
 1.2

PASCAL
The SI derived unit for pressure (Pa). One pascal is equal to 1 N/m². Pressures are often used in parametric CRS for height measurements on a vertical axis. The unlocalized name is “pascal”.Related units SI pressure units: PASCAL
,HECTOPASCAL
.In other systems: DECIBAR
,BAR
,ATMOSPHERE
.Components: NEWTON
∕SQUARE_METRE
 Since:
 0.8

HECTOPASCAL
Unit of measurement defined as 100 pascals (1 hPa). The hectopascal is the international unit for measuring atmospheric or barometric pressure and is exactly equal to one millibar. The system unit isPASCAL
and the unlocalized name is “hectopascal”.Related units SI pressure units: PASCAL
,HECTOPASCAL
.In other systems: DECIBAR
,BAR
,ATMOSPHERE
.Components: NEWTON
∕SQUARE_METRE
 Since:
 0.8

DECIBAR
Unit of measurement defined as 10000 pascals (1 dbar). This unit is used in oceanography as there is an approximate numerical equivalence between pressure changes in decibars and depth changes in metres underwater. The system unit isPASCAL
and the unlocalized name is “decibar”.Related units SI pressure units: PASCAL
,HECTOPASCAL
.In other systems: DECIBAR
,BAR
,ATMOSPHERE
.Components: NEWTON
∕SQUARE_METRE
 Since:
 0.8

BAR
Unit of measurement defined as 100000 pascals (1 bar). One bar is slightly less than the average atmospheric pressure on Earth at sea level. One millibar is exactly equal to one hectopascal. The system unit isPASCAL
and the unlocalized name is “bar”.Related units SI pressure units: PASCAL
,HECTOPASCAL
.In other systems: DECIBAR
,BAR
,ATMOSPHERE
.Components: NEWTON
∕SQUARE_METRE
 Since:
 0.8

ATMOSPHERE
Unit of measurement defined as 101325 pascals (1 atm). One atmosphere reflects the pressure at the mean sea level for countries around 49°N of latitude. The system unit isPASCAL
and the unlocalized name is “atmosphere”.Related units SI pressure units: PASCAL
,HECTOPASCAL
.In other systems: DECIBAR
,BAR
,ATMOSPHERE
.Components: NEWTON
∕SQUARE_METRE
 Since:
 0.8

NEWTON
The SI derived unit for force (N). One newton is the force required to give a mass of 1 kg an acceleration of 1 m/s². The unlocalized name is “newton”. Since:
 0.8

JOULE
The SI derived unit for energy (J). The unlocalized name is “joule”. Since:
 0.8

WATT
The SI derived unit for power (W). One watt is equal to one joule per second. The unlocalized name is “watt”. Since:
 0.8

VOLT
The SI derived unit for electric potential difference (V). The unlocalized name is “volt”. Since:
 0.8

AMPERE
The SI base unit for electric current (A). The unlocalized name is “ampere”. Since:
 0.8

COULOMB
The SI derived unit for electric charge (C). One coulomb is the charge transferred by a current of one ampere during one second. The unlocalized name is “coulomb”. Since:
 0.8

FARAD
The SI derived unit for electric capacitance (F). The unlocalized name is “farad”. Since:
 0.8

OHM
The SI derived unit for electric resistance (Ω). This is the inverse of electric conductance. The unlocalized name is “ohm”. Since:
 0.8

SIEMENS
The SI derived unit for electric conductance (S). This is the inverse of electric resistance. The unlocalized name is “siemens”. Since:
 0.8

WEBER
The SI derived unit for magnetic flux (Wb). The unlocalized name is “weber”. Since:
 0.8

TESLA
The SI derived unit for magnetic flux density (T). The unlocalized name is “tesla”.Related units Components: WEBER
∕SQUARE_METRE
 Since:
 0.8

HENRY
The SI derived unit for inductance (H). The unlocalized name is “henry”. Since:
 0.8

KELVIN
The SI base unit for thermodynamic temperature (K). The unlocalized name is “kelvin”.Related units SI temperature units: KELVIN
.In other systems: CELSIUS
,FAHRENHEIT
. Since:
 0.8

CELSIUS
Unit of measurement defined as the temperature in Kelvin minus 273.15. The symbol is °C and the unlocalized name is “Celsius”. Note that this is the only SI unit with an uppercase letter in its name.Related units SI temperature units: KELVIN
.In other systems: CELSIUS
,FAHRENHEIT
. Since:
 0.8

FAHRENHEIT
Unit of measurement defined as 1.8 degree Celsius plus 32. The symbol is °F and the unlocalized name is “Fahrenheit” (note the uppercase "F" letter). Since:
 0.8

CANDELA
The SI base unit for luminous intensity (cd). The unlocalized name is “candela”. Since:
 0.8

LUMEN
The SI derived unit for luminous flux (lm). The unlocalized name is “lumen”. Since:
 0.8

LUX
The SI derived unit for illuminance (lx). The unlocalized name is “lux”.Related units Components: LUX
∕SQUARE_METRE
 Since:
 0.8

GRAM
A SI conventional unit for mass (g). The unlocalized name is “gram”. Since:
 0.8

KILOGRAM
The SI base unit for mass (kg). The unlocalized name is “kilogram”. Since:
 0.8

MOLE
The SI base unit for amount of substance (mol). The unlocalized name is “mole”. Since:
 0.8

UNITY
The base dimensionless unit for scale measurements. The unlocalized name is “unity” and the identifier is EPSG:9201. This is the base of all other scale units:PERCENT
(%),PPM
(ppm) andPIXEL
(px) among others. Since:
 0.8

PERCENT
Dimensionless unit for percentages (%). The system unit isUNITY
and the unlocalized name is “percentage”. 
PPM
Dimensionless unit for parts per million (ppm). The system unit isUNITY
, the unlocalized name is “parts per million” and the identifier is EPSG:9202. 
DECIBEL
Subdivision of logarithm of ratio of the measured quantity to a reference quantity (dB). Since:
 1.0

PSU
Salinity measured using PSS78. While this is a dimensionless measurement, the"psu"
symbol is sometimes added to PSS78 measurement. However, this is officially discouraged. Since:
 0.8

PIXEL
Dimensionless unit for pixels (px). The unlocalized name is “pixel”. This unity should not be confused withPOINT
, which is approximately equal to 1/72 of inch. See Also:


Method Details

isAngular
Returnstrue
if the given unit is a linear unit. Linear units are convertible toDEGREE
.Angular units are dimensionless, which may be a cause of confusion with other dimensionless units like
UNITY
orPPM
. This method take care of differentiating angular units from other dimensionless units. Parameters:
unit
 the unit to check (may benull
). Returns:
true
if the given unit is nonnull and angular. See Also:

isLinear
Returnstrue
if the given unit is a linear unit. Linear units are convertible toMETRE
. Parameters:
unit
 the unit to check (may benull
). Returns:
true
if the given unit is nonnull and linear. See Also:

isPressure
Returnstrue
if the given unit is a pressure unit. Pressure units are convertible toPASCAL
. Those units are sometimes used instead of linear units for altitude measurements. Parameters:
unit
 the unit to check (may benull
). Returns:
true
if the given unit is nonnull and a pressure unit.

isTemporal
Returnstrue
if the given unit is a temporal unit. Temporal units are convertible toSECOND
. Parameters:
unit
 the unit to check (may benull
). Returns:
true
if the given unit is nonnull and temporal. See Also:

isScale
 Parameters:
unit
 the unit to check (may benull
). Returns:
true
if the given unit is nonnull and a dimensionless scale. See Also:

ensureAngular
Makes sure that the specified unit is either null or an angular unit. This method is used for argument checks in constructors and setter methods. Parameters:
unit
 the unit to check, ornull
if none. Returns:
 the given
unit
argument, which may be null.  Throws:
IllegalArgumentException
 ifunit
is nonnull and not an angular unit. See Also:

ensureLinear
Makes sure that the specified unit is either null or a linear unit. This method is used for argument checks in constructors and setter methods. Parameters:
unit
 the unit to check, ornull
if none. Returns:
 the given
unit
argument, which may be null.  Throws:
IllegalArgumentException
 ifunit
is nonnull and not a linear unit. See Also:

ensureTemporal
Makes sure that the specified unit is either null or a temporal unit. This method is used for argument checks in constructors and setter methods. Parameters:
unit
 the unit to check, ornull
if none. Returns:
 the given
unit
argument, which may be null.  Throws:
IllegalArgumentException
 ifunit
is nonnull and not a temporal unit. See Also:

ensureScale
Makes sure that the specified unit is either null or a scale unit. This method is used for argument checks in constructors and setter methods. Parameters:
unit
 the unit to check, ornull
if none. Returns:
 the given
unit
argument, which may be null.  Throws:
IllegalArgumentException
 ifunit
is nonnull and not a scale unit. See Also:

multiply
public static <Q extends Quantity<Q>> Unit<Q> multiply(Unit<Q> unit, double numerator, double denominator) Multiplies the given unit by the given ratio. For example, multiplyingCENTIMETRE
by 254/100 givesINCH
. Invoking this method is equivalent to invokingUnit.multiply(numerator / denominator)
except that the use of a ration of integer values help Apache SIS to improve accuracy when more than one arithmetic operation are chained. Type Parameters:
Q
 the quantity measured by the unit. Parameters:
unit
 the unit to multiply.numerator
 the numerator of the multiplication factor.denominator
 the denominator of the multiplication factor. Returns:
 the unit multiplied by the given factor.
 Since:
 0.8

toStandardUnit
Returns the factor by which to multiply the standard unit in order to get the given unit. The "standard" unit is usually the SI unit on which the given unit is based, as given byUnit.getSystemUnit()
.Example: if the given unit isIf the given unit isKILOMETRE
, then this method returns 1000 since a measurement in kilometres must be multiplied by 1000 in order to give the equivalent measurement in the "standard" units (hereMETRE
).null
or if the conversion to the "standard" unit cannot be expressed by a single multiplication factor, then this method returnsDouble.NaN
. Type Parameters:
Q
 the quantity measured by the unit, ornull
. Parameters:
unit
 the unit for which we want the multiplication factor to standard unit, ornull
. Returns:
 the factor by which to multiply a measurement in the given unit in order to get an equivalent measurement in the standard unit, or NaN if the conversion cannot be expressed by a scale factor.

converter
Creates a linear converter from the given scale and offset. Parameters:
scale
 the scale factor, ornull
if none (default value of 1).offset
 the offset, ornull
if none (default value of 0). Returns:
 a converter for the given scale and offset.
 Since:
 1.0
 See Also:

coefficients
Returns the coefficients of the given converter expressed as a polynomial equation. This method returns the first of the following choices that apply: If the given converter is identity, returns an empty array.
 If the given converter shifts the values without scaling them (for example the conversion from Kelvin to Celsius degrees), returns an array of length 1 containing only the offset.
 If the given converter scales the values (optionally in addition to shifting them), returns an array of length 2 containing the offset and scale factor, in that order.
null
if it cannot get the polynomial equation coefficients from the given converter. Parameters:
converter
 the converter from which to get the coefficients of the polynomial equation, ornull
. Returns:
 the polynomial equation coefficients (may be any length, including zero), or
null
if the given converter isnull
or if this method cannot get the coefficients.  Since:
 0.8

derivative
Returns the derivative of the given converter at the given value, orNaN
if this method cannot compute it. Parameters:
converter
 the converter for which we want the derivative at a given point, ornull
.value
 the point at which to compute the derivative. Ignored (can beDouble.NaN
) if the conversion is linear. Returns:
 the derivative at the given point, or
NaN
if unknown.  See Also:

valueOf
Parses the given symbol. Invoking this method is equivalent to invokingUnitFormat.parse(CharSequence)
on a shared localeindependent instance. This method is capable to handle some symbols found during WKT parsing or in XML files. The list of symbols supported by this method is implementationdependent and may change in future SIS versions.Parsing authority codes
If the givenuom
arguments is of the form"EPSG:####"
,"urn:ogc:def:uom:EPSG:####"
or"http://www.opengis.net/def/uom/EPSG/0/####"
(ignoring case and whitespaces around separators), then"####"
is parsed as an integer and forwarded to thevalueOfEPSG(int)
method.Note on netCDF unit symbols
In netCDF files, values of "unit" attribute are concatenations of an angular unit with an axis direction, as in"degrees_east"
or"degrees_north"
. ThisvalueOf(…)
method ignores those suffixes and unconditionally returnsDEGREE
for all axis directions. Parameters:
uom
 the symbol to parse, ornull
. Returns:
 the parsed symbol, or
null
ifuom
was null.  Throws:
ParserException
 if the given symbol cannot be parsed. See Also:

valueOfEPSG
Returns a hardcoded unit from an EPSG code. Thecode
argument given to this method shall be a code identifying a record in the"Unit of Measure"
table of the EPSG geodetic dataset. If this method does not recognize the given code, then it returnsnull
.The list of units recognized by this method is not exhaustive. This method recognizes the base units declared in the
TARGET_UOM_CODE
column of the abovecited table, and some frequentlyused units. The list of recognized units may be updated in any future version of SIS.The
EPSGDataAccess
class uses this method for fetching the base units, and derives automatically other units from the information found in the EPSG database. This method is also used by other classes not directly related to the EPSG database, likeCommonAuthorityFactory
which uses EPSG codes for identifying units.The currently recognized values are:
EPSG codes for units Angular units Code Unit 9101 radian 9102 decimal degree 9103 minute 9104 second 9105 grad 9107 degreeminutesecond 9108 degreeminutesecond 9109 microradian 9110 sexagesimal degreeminutesecond 9111 sexagesimal degreeminute 9122 decimal degree Linear units Code Unit 1025 millimetre 1033 centimetre 9001 metre 9002 foot 9003 US survey foot 9030 nautical mile 9036 kilometre 9093 statute mile Time units Code Unit 1029 year 1040 second Scale units Code Unit 9201 unity 9202 parts per million 9203 unity Note: EPSG uses code 9102 (degree) for prime meridian and coordinate operation parameters, and code 9122 (degree (supplier to define representation)) for coordinate system axes. But Apache SIS considers those two codes as synonymous. Parameters:
code
 the EPSG code for a unit of measurement. Returns:
 the unit, or
null
if the code is unrecognized.  See Also:

getEpsgCode
Returns the EPSG code of the given units, ornull
if unknown. This method is the converse ofvalueOfEPSG(int)
.The same unit may be represented by different EPSG codes depending on the context:
 EPSG:9102 – degree – is used for prime meridian and coordinate operation parameters.
 EPSG:9122 – degree (supplier to define representation) – is used for coordinate system axes.
inAxis
argument, which specifies whether the code will be used for axis definition or in other context. Parameters:
unit
 the unit for which to get the EPSG code.inAxis
true
for a unit used in Coordinate System Axis definition. Returns:
 the EPSG code of the given units, or
null
if unknown.  Since:
 0.4
 See Also:
