earthtrack - Combine xplanet and predict
earthtrack [ -h <predictservername> ] [ -p <proj> ] [ -x <arguments
for xplanet> ] [ -u <screen update interval> ] [ -o <send output to
image file (default: /tmp/xplanet.png)> ] [ -c <satellite> ] [ -C
"earthtrack" uses "xplanet" to produce an orthographic image of the
earth upon which satellite names are placed over their respective sub-
satellite points. The globe can be centered either over your
groundstation location (default), or over the location any satellite
being tracked by PREDICT. The second method allows you to "fly with
the satellite" as it circles the globe. The map is updated every 20
seconds. By default, "earthtrack" connects to the PREDICT server
running on "localhost". These defaults may be overridden through
several command-line switches.
The -h switch allows a different PREDICT server name to be specified.
The -x switch option allows additional command-line parameters to be
passed to xplanet through earthtrack. (Note that the argument that
follows the -x switch must be enclosed in "quotes".) The -u switch
allows a different map update interval to be specified, and the -c
switch allows the map to be centered on a specific satellite.
earthtrack -c ISS -u 15 -h predictserver.org
allows earthtrack to invoke "xearth" as a display, centering the map on
the location of satellite "ISS", using host "predictserver.org" as the
host running PREDICT in server mode. The satellite name specified must
be the same as PREDICT displays in Multi-Tracking mode. If a space
appears in the name, then the entire name must be enclosed in double
"xplanet" uses highly detailed photo-realistic maps of the world
available from a variety of sources to produce spectacular views of the
earth. For example, if an uppercase -C is used rather than a lowercase
-c for the map center switch, such as in the following example:
earthtrack -C ISS
the map is not only centered on the location of the ISS, but the map is
also zoomed into an area slightly larger than the footprint of the
satellite. A range circle is also drawn on the map to indicate the
actual footprint of the spacecraft at the current time.
If a map centered on the groundstation location is desired, then
footprint range circles for neighboring satellites are drawn on the
map. Range circles are drawn for satellites between 5 minutes prior to
AOS through the point of LOS. Such a display may be created simply by
executing "earthtrack" without any switches:
or with the -h switch to identify the remote host running PREDICT in
earthtrack -h predictserver.org
If the satellite being tracked is in sunlight, then the satellite name
and range circle are displayed in white. If the satellite is in
darkness, then the color blue is used. If the satellite is optically
visible to the groundstation, then yellow is used.
"earthtrack" may also be used to generate graphics files for use in web
server environments. For example:
earthtrack2 -c ISS -x "-geometry 800x600 -output graphic.png"
will invoke "xplanet" to produce an 800x600 PNG image of the world
centered on the sub-satellite point of the ISS with a name of
"graphic.png". This feature, along with capabilities demonstrated in
the ~/predict/clients/samples directory, can be used to develop
satellite tracking and orbital prediction content for a web server.
"earthtrack" exits when its connection to the PREDICT server is broken,
such as would occur if PREDICT is terminated while "earthtrack" is
still running. The application may be run as background processes by
placing an ampersand (&) at the end of the command line.
This version includes a -o switch to send the output to the file
/tmp/xplanet.png instead of to the screen.
For more creative uses of PREDICT and earthtrack, see John Heaton,
G1YYH’s PREDICT and earthtrack modification web page at:
73, de John, KD2BD
-c <satellite> (center on satellite)
-C <satellite> (center on satellite and zoom in)
-h <hostname running predict in server mode>
-o <output to image file>
-x <command line arguments to pass along to xplanet>
-u <screen update interval in seconds>
This man page was written by A. Maitland Bottoms, AA4HS, for Debian
31 August 2003