Unit conversion

Convert between various distance and time units.

Options

+xy_in

Input unit of the horizontal components.

+xy_out

Output unit of the horizontal components.

+z_in

Input unit of the vertical component.

+z_out

Output unit of the vertical component.

+t_in

Input unit of the time component.

+t_out

Output unit of the time component.

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 GNNS 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 ...

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.

mjd

Modfied Julian date

decimalyear

Decimal year

gps_week

GPS Week