Unit conversion¶

New in version 5.0.0.

Convert between various distance and time units.

Alias	unitconvert
Domain	2D, 3D or 4D
Input type	Any
Output type	Any

There are many examples of coordinate reference systems that are expressed in other units than the meter. There are also many cases where temporal data has to be translated to different units. The unitconvert operation takes care of that.

Many North American systems are defined with coordinates in feet. For example in Vermont:

+proj=pipeline
+step +proj=tmerc +lat_0=42.5 +lon_0=-72.5 +k=0.999964286 +x_0=500000.00001016 +y_0=0
+step +proj=unitconvert +xy_in=m +xy_out=us-ft

Often when working with GNSS data the timestamps are presented in GPS-weeks, but when the data transformed with the helmert operation timestamps are expected to be in units of decimalyears. This can be fixed with unitconvert:

+proj=pipeline
+step +proj=unitconvert +t_in=gpsweek +t_out=decimalyear
+step +proj=helmert +epoch=2000.0 +t_obs=2017.5 ...

Parameters¶

+xy_in=<unit>¶: Horizontal input units. See Distance units for a list of available units.

+xy_out=<unit>¶: Horizontal output units. See Distance units for a list of available units.

+z_in=<unit>¶: Vertical output units. See Distance units for a list of available units.

+z_out=<unit>¶: Vertical output units. See Distance units for a list of available units.

+t_in=<unit>¶: Temporal input units. See Time units for a list of available units.

+t_out=<unit>¶: Temporal output units. See Time units for a list of available units.

Distance units¶

In the table below all distance units supported by PROJ is listed. The same list can also be produced on the command line with proj or cs2cs, by adding the -lu flag when calling the utility.

Label	Name
km	Kilometer
m	Meter
dm	Decimeter
cm	Centimeter
mm	Millimeter
kmi	International Nautical Mile
in	International Inch
ft	International Foot
yd	International Yard
mi	International Statute Mile
fath	International Fathom
ch	International Chain
link	International Link
us-in	U.S. Surveyor’s Inch
us-ft	U.S. Surveyor’s Foot
us-yd	U.S. Surveyor’s Yard
us-ch	U.S. Surveyor’s Chain
us-mi	U.S. Surveyor’s Statute Mile
ind-yd	Indian Yard
ind-ft	Indian Foot
ind-ch	Indian Chain

Time units¶

In the table below all time units supported by PROJ is listed.

label	Name
mjd	Modified Julian date
decimalyear	Decimal year
gps_week	GPS Week
yyyymmdd	Date in yyyymmdd format