NAME
xplanet - render an image of a planet into an X window or file
SYNOPSIS
xplanet [options]
DESCRIPTION
Xplanet is similar to Xearth, where an image of the earth is rendered
into an X window. All of the major planets and most satellites can be
drawn. A number of different map projections are also supported,
including azimuthal, Mercator, Mollweide, orthographic, and
rectangular. The latest version can always be found at
http://xplanet.sourceforge.net.
OPTIONS
Options need only be specified with enough characters to be
unambiguous. Valid options to Xplanet are:
-arc_file
Specify an arc file to be plotted against the background stars.
Each line in the file must have the following syntax:
dec1 ra1 dec2 ra2
where declination is in degrees and right ascension is in hours.
This option has no effect if -projection is specified.
-arc_spacing spacing
When drawing an arc, draw line segments that are spacing degrees
apart. The default is 0.1 degrees. Line segments shorter than
spacing will not be drawn.
-arc_thickness thickness
Specify the thickness of arcs. The default is 1 pixel. When
drawing arcs on a planet using the arc_file option in the
configuration file, use the arc_thickness option there too.
-background background_file
Use background_file as the background image, with the planet to
be superimposed upon it. A color may also be supplied (e.g.
-background "navy blue" or -background 0xff00ff).
-base_magnitude magnitude
A star of the specified magnitude will have a pixel brightness
of 1. The default value is 10. Stars will be drawn more
brightly if this number is larger.
-body body
Render an image of the specified planet or satellite. Valid
values for body are sun, mercury, venus, earth, moon, mars,
phobos, deimos, jupiter, io, europa, ganymede, callisto, saturn,
mimas, enceladus, tethys, dione, rhea, titan, hyperion, iapetus,
phoebe, uranus, miranda, ariel, umbriel, titania, oberon,
neptune, triton, nereid, pluto, charon, random, and major.
The field of view can also be centered on a satellite location
using "naif" or "norad", along with the satellite id. For
example, "-body naif-82" will center the field of view on NAIF
ID -82, which is the Cassini orbiter. Xplanet must be compiled
with SPICE support and the required kernels must be present.
See the README in the spice subdirectory for more details.
Using "-body norad20580" will center the field of view on NORAD
ID 20580, which is the Hubble Space Telescope. The appropriate
TLE files must be present in this case. See the README in the
satellites subdirectory for more information.
Using "path" will center the field of view on the direction of
motion of the origin. This direction is relative to the
direction of motion of the body specified by -path_relative_to.
Earth is the default body. This option is the same as -target.
-center +x+y
Place the center of the rendered body at pixel coordinates (x,
y). The upper left corner of the screen is at (0,0). Either x
or y may be negative. The default value is the center of the
screen.
-color color
Set the color for the label. The default is "red". Any color
in the rgb.txt file may be used. Colors may also be specified
by RGB hex values; for example -color 0xff and -color blue mean
the same thing, as do -color 0xff0000 and -color red.
-config config_file
Use the configuration file config_file. The format of
config_file is described in README.config. See the description
of -searchdir to see where xplanet looks in order to find the
configuration file.
-date YYYYMMDD.HHMMSS
Use the date specified instead of the current local time. The
date is assumed to be GMT.
-date_format string
Specify the format for the date/time label. This format string
is passed to strftime(3). The default is "%c %Z", which shows
the date, time, and time zone in the locale’s appropriate date
and time representation.
-dynamic_origin file
Specify an observer location. The location is relative to the
body specified with -origin (by default, this is the Sun). The
last line of the file must be of the form
YYYYMMDD.HHMMSS range lat lon localtime
For example,
19951207.120000 10.328 -3.018 97.709 9.595
The specified time is ignored and the current time is used. The
range is in planetary radii, and lat and lon are in degrees.
Localtime (in hours) is optional, but if present, it will be
used in place of the longitude. Only the last line of the file
is used. This file may be updated between renderings using a
script executed with the -prev_command or -post_command options.
-ephemeris_file filename
Specify a JPL digital ephemeris file (DE200, DE405, or DE406) to
use for computing planetary positions. Xplanet uses Bill Gray’s
code (http://www.projectpluto.com/jpl_eph.htm), which reads both
big and little endian binary files. The ephemeris files found
at ftp://ssd.jpl.nasa.gov/pub/eph/export/unix are big endian
files, but you do not need to do any additional byte-swapping to
use them. See the description of -searchdir to see where
xplanet looks in order to find the ephemeris file.
-font fontname
Set the font for the label. Only TrueType fonts are supported.
If the -pango option is used, fontname is taken to be the font
family name (e.g. "Arial").
-fontsize size
Specify the point size. The default is 12.
-fork Detach from the controlling terminal. This is useful on MS
Windows to run xplanet from a batch file without having to keep
a DOS window open. Be careful when using this option; it’s easy
to have multiple processes running at the same time without
knowing it - check the Task Manager. On unix systems this is
pretty much the same as running xplanet in the background.
-fov Specify the field of view, in degrees. This option and the
-radius option are mutually exclusive. This option has no
effect if the -projection option is used.
-geometry string
Specify the image geometry using the standard X window geometry
syntax, [<width>{xX}<height>][{+-}<xoffset>{+-}<yoffset>] (e.g.
256x256-10+10 puts a window 256x256 pixels in size 10 pixels
away from the right side and 10 pixels below the top of the root
window). The root window outside of the image will be black.
This option may be used with -window or -output.
-glare radius
Draw a glare around the sun with with a radius of the specified
value larger than the sun. The default value is 28.
-gmtlabel
Same as the -label option, but show GMT instead of local time.
-grs_longitude lon
The longitude of Jupiter’s Great Red Spot (GRS). A typical
value is 94 degrees. If this option is specified, longitudes on
Jupiter will be calculated in System II coordinates. By
default, longitudes are calculated in System III coordinates.
When using this option, use an image map for Jupiter where the
center of the GRS is at the pixel 0 column, or the left side of
the image.
-hibernate seconds
After the screen has been idle for the specified number of
seconds, xplanet will sleep. This option requires xplanet to
have been compiled with the X Screensaver extension.
-idlewait seconds
Don’t run Xplanet unless the screen has been idle for the
specified number of seconds. This option requires xplanet to
have been compiled with the X Screensaver extension.
-interpolate_origin_file
This option is only useful in conjunction with -origin_file. It
computes the observer position at the current time by
interpolating between values specified in the origin file. This
is useful if you have spacecraft positions tabulated in an
origin file, but want a real time view.
-jdate Julian date
Use the specified Julian date instead of the current local time.
-label Display a label in the upper right corner.
-labelpos
Specify the location of the label using the standard X window
geometry syntax. The default position is "-15+15", or 15 pixels
to the left and below the top right corner of the display. This
option implies -label.
-label_body body
Use the specified body to calculate the sub-observer, sub-solar,
and illumination values in the label. This is useful with the
-separation option.
-label_string
Specify the text of the first line of the label. By default, it
says something like "Looking at Earth". Any instances of %t
will be replaced by the target name, and any instances of %o
will be replaced by the origin name.
-latitude latitude
Render the target body as seen from above the specified latitude
(in degrees). The default value is 0.
-light_time
Account for the time it takes for light to travel from the
target body to the observer. The default is to ignore the
effects of light time.
-log_magstep step
Increase the brightness of a star by 10^step for each integer
decrease in magnitude. The default value is 0.4. This means
that a star of magnitude 2 is 10^0.4 (about 2.5) times brighter
than a star of magnitude 3. A larger number makes stars
brighter.
-longitude longitude
Place the observer above the specified longitude (in degrees).
Longitude is positive going east, negative going west (for the
earth and moon), so for example Los Angeles is at -118 or 242.
The default value is 0.
-make_cloud_maps
If there is an entry in the config file for cloud_map, xplanet
will output a day and night image with clouds overlaid and then
exit. The images will be created in the directory specified by
-tmpdir, or in the current directory if -tmpdir is not used.
The names of the output images default to day_clouds.jpg and
night_clouds.jpg, but may be changed by the -output option. If
"-output filename.extension" is specified, the output images
will be named "day_filename.extension" and
"night_filename.extension". The dimensions of the output images
are the same as the day image.
-marker_file
Specify a file containing user defined marker data to display
against the background stars. The format of each line is
generally declination, right ascension, string, as in the
example below:
-16.7161 6.7525 "Sirius"
For additional options which may be specified, see the
marker_file entry in README.config. This option has no effect
if -projection is specified. This option is not meant for city
markers; for that use the marker_file option in the
configuration file.
-markerbounds filename
Write coordinates of the bounding box for each marker to
filename. This might be useful if you’re using xplanet to make
imagemaps for web pages. Each line looks like:
204,312 277,324 Los Angeles
where the coordinates are for the upper left and lower right
corners of the box. This file gets rewritten every time xplanet
renders its image.
-north north_type
This option rotates the image so that the top points to
north_type. Valid values for north_type are:
body: body’s north pole
galactic: galactic north pole
orbit: body’s orbital north pole (perpendicular to the orbit plane)
path: origin’s velocity vector (also see -path_relative_to option)
separation: perpendicular to the line of sight and the
target-separation target line (see -separation option)
The default value is "body".
-num_times num_times
Run num_times before exiting. The default is to run
indefinitely.
-origin body
Place the observer at the center of the specified body. Valid
values are the same as for -target. In addition, "above",
"below", or "system" may be specified. Using "above" or "below"
centers the view on the body’s primary and the field of view is
large enough to show the body’s orbit. Using "system" places
the observer at the center of a random body in the same system
as the target body. Two bodies are in the same system if one of
the following is true:
1) target and origin have same primary
2) target is origin’s primary
3) origin is target’s primary
If the body name is preceded by a dash, the observer is placed
on the opposite side of the target from the specified body at a
distance equal to the distance between the target and body. For
example, -target earth -origin sun places the observer at the
center of the sun. If -target earth -origin -sun is used, the
observer is placed on a line connecting the centers of the earth
and sun at a distance of 1 AU farther from the sun than the
earth.
-origin_file origin_file
Specify a list of observer positions in origin_file. The
positions are relative to the body specified with -origin (by
default, this is the Sun). Each line should be of the form
YYYYMMDD.HHMMSS range lat lon localtime
For example,
19951207.120000 10.328 -3.018 97.709 9.595
Range is in planetary radii, and lat and lon are in degrees.
The date is the only required value. If the localtime (in
hours) is supplied, it will be used in place of the longitude.
For each line in the origin file, the observer is placed at the
specified position, relative to the body specified with -origin.
This option is useful for showing spacecraft flybys or orbiting
around a planet. Any line with a # in the first column is
ignored.
-output filename
Output to a file instead of rendering to a window. The file
format is taken from the extension. Currently .gif, .jpg, .ppm,
.png, and .tiff images can be created, if xplanet has been
compiled with the appropriate libraries. The image size
defaults to 512 by 512 pixels but this may be changed by the
-geometry flag. If used with the -num_times option, each output
file will be numbered sequentially.
-output_start_index index
Start numbering output files at index. The default is 0.
-pango Use the Pango (http://www.pango.org) library for rendering
internationalized text. Pango uses Unicode for all of its
encoding, and will eventually support output in all the worlds
major languages. If xplanet has not been compiled with this
library this option will be ignored. There appear to be memory
leaks in the pango library, so I don’t recommend letting xplanet
run indefinitely with this option.
-path_relative_to body
Only used with -north path or -target path. The origin’s
velocity vector is calculated relative to the specified body.
By default, this is the Sun.
-post_command command
-prev_command command
Run command either before or after each time xplanet renders an
image. On MS Windows, you may need to use unix-style paths.
For example:
xplanet.exe -prev_command ./prev.bat
-print_ephemeris
Print the heliocentric rectangular equatorial coordinates
(J2000) for each body xplanet knows about, and then exit.
-projection projection_type
The projection type may be one of ancient, azimuthal, bonne,
equal_area, gnomonic, hemisphere, lambert, mercator, mollweide,
orthographic, peters, polyconic, rectangular, or tsc. The
default is no projection. Multiple bodies will not be shown if
this option is specified, although shadows will still be drawn.
-proj_param value
Pass additional parameters for some projections. The only
projections that use this option at present are the Bonne,
Gnomonic, and Mercator projections. The Bonne projection is
conformal at the specified latitude. Higher values lead to a
thinner heart shape. The default is 50 degrees. The Gnomonic
and Mercator projections use the specified latitude as the
boundaries of the projection. The defaults are 45 and 80
degrees, respectively. This option may be used more than once
for future projections that require additional parameters. Only
the first value is used at present.
-quality quality
This option is only used when creating JPEG images. The quality
can range from 0 to 100. The default value is 80.
-radius radius
Specify the radius of the globe as a percent of the screen
height. The default value is 45% of the screen height. When
drawing Saturn, the radius value applies to the radius of the
outer ring.
-random
Place the observer above a random latitude and longitude.
-range range
Render the globe as seen from a distance of range from the
planet’s center, in units of the planetary radius. The default
value is 1000. Note that if you use very close ranges the field
of view of the screen can be greater than 180 degrees! If you
want an "up close" image use the -radius option.
-rotate angle
Rotate the globe by angle degrees counterclockwise so that north
(as defined by the -north argument) isn’t at the top. The
default value is 0. My friends in the Southern Hemisphere can
use -rotate 180 to make the earth look like it should! For non-
orthographic projections, the globe is rotated and then
projected, if that helps you visualize what to expect.
-save_desktop_file
On Microsoft Windows and Mac OS X, xplanet creates an
intermediate image file which is used to set the desktop. This
file will be created in the -tmpdir directory. By default, this
image is removed after the desktop has been set. Specifying
this option will leave the file in place.
-searchdir directory
Any files used by xplanet should be placed in one of the
following directories depending on its type: "arcs", "config",
"ephemeris", "fonts", "images", "markers", "origin",
"satellites", or "stars". By default, xplanet will look for a
file in the following order:
The current directory
searchdir
subdirectories of searchdir
subdirectories of xplanet (if it exists in the current directory)
subdirectories of ${HOME}/.xplanet on X11
subdirectories of ${HOME}/Library/Xplanet on Mac OS X
subdirectories of DATADIR/xplanet
DATADIR is set at compile time and defaults to /usr/local/share.
-separation body:dist
Place the observer at a location where the target body and the
separation body are dist degrees apart. For example "-target
earth -separation moon:-3" means place the observer at a
location where the moon appears 3 degrees to the left of the
earth.
-spice_ephemeris index
Use SPICE kernels to compute the position of the named body.
The index is the naif ID code (e.g. 599 for Jupiter). The
-spice_file option must be used to supply the names of the
kernel files. This option may be used more than once for
different bodies.
-spice_file spice_file
Specify a file containing a list of objects to display. A file
containing a list of SPICE kernels to read named spice_file.krn
must exist along with spice_file. See the README in the "spice"
subdirectory for more information.
-starfreq frequency
Fraction of background pixels that will be colored white. The
default value is 0.001. This option is only meaningful with the
azimuthal, mollweide, orthographic, and peters projections.
-starmap starmap
Use starmap to draw the background stars. This file should be a
text file where each line has the following format:
Declination, Right Ascension, Magnitude
where Declination is in decimal degrees and Right Ascension is
in decimal hours. For example, the entry for Sirius is
-16.7161 6.7525 -1.46
See the description of -searchdir to see where xplanet looks in
order to find the star map.
-target target
Same as -body.
-tt Use terrestrial time instead of universal time. The two differ
slightly due to the non-uniform rotation of the earth. The
default is to use universal time.
-timewarp
As in xearth, scale the apparent rate at which time progresses
by factor. The default is 1.
-tmpdir tmpdir
Specify a directory that xplanet will use to place images
created using -make_cloud_maps. On Microsoft Windows, xplanet
will write a bitmap file called xplanet.bmp to the specified
directory. The default is the result of the GetWindowsDirectory
call (C:WINDOWS on Win95). On Mac OS X, xplanet will create an
intermediate PNG file in order to set the background. The
default value is /tmp. On Windows and Mac OS X, the
intermediate file will be removed unless the -save_desktop_file
option is specified.
-transparency
Update the background pixmap for transparent Eterms and aterms.
This option only works under X11.
-transpng filename
Same as the -output option, except set the background to be
transparent when writing a PNG file.
-utclabel
Same as -gmtlabel.
-verbosity level
level output
< 0 only fatal error messages
0 non-fatal warning messages
1 basic information
2 basic diagnostics
3 more detailed diagnostics
4 very detailed diagnostics
The default value is 0.
-version
Display current version information, along with a list of
compile-time options that xplanet supports.
-vroot Render the image to the virtual root window. Some window
managers use one big window that sits over the real root window
as their background window. Xscreensaver uses a virtual root
window to cover the screen as well.
-wait wait
Update every wait seconds.
-window
Render the image to its own X window. The size defaults to 512
by 512 pixels but this may be set by the -geometry flag.
-window_title title
Set the window’s title to title. This option implies -window.
-xscreensaver
Same as -vroot.