GeodeZYX Toolbox’s Cookbook¶
Convert time¶
The GeodeZYX Toolbox can handle a lot of time scales and time representations.
What we call scale is a physical definition: UTC, GPS Time, TAI…
What we call representation is the way the physical value is represented : Julian date, year/day of year, GPS week/day of week, ISO string…
The basic idea behind it is the conversion to and from the datetime objects of the Python’s datetime module.
The generic structure of the fuctions is conv.<input time scale/representation>2<output time scale/representation>.
Complete reference¶
All the module’s functionalites can be found here:
geodezyx.conv.conv_time
Time conversion exemples¶
First of all:
import geodezyx.conv as conv # Import the conversion module
import datetime as dt
Get today as GPS Time (week/day of week)¶
now = dt.datetime.now() ### datetime.datetime(2021, 6, 18, 15, 53, 56, 245345)
gpstime = conv.dt2gpstime(now)
gpstime
Out: (2162, 5)
Convert year/day of year to Modified Julian Day¶
year,doy = (2021, 169)
epoch = conv.doy(year, doy)
mjd = conv.dt2MJD(epoch)
mjd
Out: 59383.0
Convert a SP3 name to decimal year¶
p = "/home/user/igs20726.sp3"
epoch = conv.sp3name2dt(p)
yeardec = conv.dt2year_decimal(epoch)
yeardec
Out: 2019.739611872146
It handles also RINEX names with conv.rinexname2dt(p_rinex) (old and new naming)
(Documentation here: geodezyx.conv.conv_time.rinexname2dt())
Convert coordinates¶
The GeodeZYX Toolbox can easily handle coordinate conversion in Geocentric (X,Y,Z), Geographic (latitude, longitude, height) and topocentric (East, North, Up).
Warning: This is considered as the “low-level” coordinate conversions. It does not deal with the different Reference Frame and their realisations (ITRFxx, ETRFxx…). This is managed by “high-level” functions in the ``reffram``module.
These functions are optimized for arrays (multiple inputs) but can also handle scalars.
Coordinates conversion exemples¶
We consider as exemple the coordinates of the Helmertturm given in latitude, longitude, height from Wikipedia and the GNSS station POTS in Geocentric XYZ.
Helmertturm = np.array([52.380278, 13.065278,147.983])
POTS = np.array([3800689.6341,882077.3857,5028791.3179 ])
We can bring POTS in Geographic and the Helmertturm in Geocentric coordinates
POTS_geo = conv.XYZ2GEO(POTS[0],POTS[1],POTS[2])
POTS_geo = conv.XYZ2GEO(*POTS)
POTS_geo
Out: (52.37929737808202, 13.066091316954145, 144.41769897658378)
Helmertturm_xyz = conv.GEO2XYZ(Helmertturm[0],
Helmertturm[1],
Helmertturm[2])
Helmertturm_xyz = conv.GEO2XYZ(*Helmertturm)
Helmertturm_xyz
Out: (89.92804903383008, 14.005569048843014, -6356604.297220887)
We can also get the vector between POTS and the Helmertturm (i.e. the Helmertturm in the Topocentric frame centered on POTS)
conv.XYZ2ENU_2(Helmertturm[0], Helmertturm[1], Helmertturm[2],
POTS[0],POTS[1],POTS[2])
Out: (array([0.88515353]), array([20735.55848087]), array([-6364723.46820732]))
Complete reference¶
All the module’s functionalites can be found here:
geodezyx.conv.conv_coords