xearth(1) User Commands xearth(1) NAME xearth - displays a shaded image of the Earth in the root window SYNOPSIS xearth [-pos _l_a_t _l_o_n ] [-noshade] [-sunpos _l_a_t _l_o_n ] [- size _w _h ] [-label] [-wait _s_e_c_s ] [-day _p_c_t ] [-night _p_c_t ] [- nofork] [-nogeostatic _l_a_t _l_o_n ] [-version] [-ppm] [-gif] [ - display _d_p_y_n_a_m_e ] DESCRIPTION _X_e_a_r_t_h sets the X root window an image of the Earth, as seen from your favorite vantage point in space, correctly shaded for the current position of the Sun. By default, _x_e_a_r_t_h forks a child process that runs in the background, updating the displayed image every five minutes to reflect changes in the Sun's position. This behavior can be changed with the - wait and -nofork options (see below). _X_e_a_r_t_h can also render directly into PPM and GIF files instead of drawing in the root window; see the -ppm and -gif options below. OPTIONS -pos _l_a_t _l_o_n Specify the point on the Earth's surface (latitude and longitude, specified in decimal degrees) around which the displayed image should be centered. If not speci- fied, this position defaults to 0 degrees latitude, 0 degrees longitude. -noshade Disable shading, use flat colors to render land and water. -sunpos _l_a_t _l_o_n Specify the point on the Earth's surface (latitude and longitude, specified in decimal degrees) where the Sun is directly overhead. By default, _x_e_a_r_t_h calculates and updates this position according to the current time. -size _w _h Specify an image _w pixels wide and _h pixels high. When rendering into the X root window, these values default to the dimensions of the root window. When producing a PPM or GIF file instead of drawing in the X root window (see the -ppm and -gif options, below), both values default to 512. -label If rendering into the X root window, also provide a MTU Last change: 14 November 1993 1 xearth(1) User Commands xearth(1) label in the lower right-hand corner that indicates the viewing position and current position of the sun. -wait _s_e_c_s Wait _s_e_c_s seconds between updates of the root window. This value defaults to 300 seconds (five minutes). -day _p_c_t Specify the brightness that should be used to shade the day side of the Earth. _P_c_t should be an integer between 0 and 100, inclusive, where 0 indicates total darkness and 100 indicates total illumination. This value defaults to 100. -night _p_c_t Specify the brightness that should be used to shade the night side of the Earth (see description of _p_c_t immedi- ately above). This value defaults to 25. -nofork If rendering into the X root window, don't "auto- background" by forking off a child process. -nogeostatic _l_a_t _l_o_n By default xearth keeps a geostatic point of view of the earth. By specifying this option, the sun stays static, and the earth rotates. the latitude and longtitude values specified, are simple offests to the viewing point. A value of zero on both, keeps the posi- tion of the sun, in the middle of the picture. -version Print what version of _x_e_a_r_t_h this is. -ppm Instead of drawing in the X root window, write a PPM file (24-bit color) to standard out. -gif Instead of drawing in the X root window, write a GIF file (8-bit color) to standard out. NOTES This man page documents _x_e_a_r_t_h version 0.5. There are a number of very useful improvements that I'd like to make (such as support for other than eight-bit pseudocolor visu- als, better error recovery, getting options via X resources, etc.), but I really should be working on my thesis instead of hacking on this. The map information used in _x_e_a_r_t_h was derived from the "CIA World Data Bank II map database," as taken from some "cbd" files that were apparently originally generated by Brian MTU Last change: 14 November 1993 2 xearth(1) User Commands xearth(1) Reid at DECWRL. The Graphics Interchange Format(c) is the Copyright property of CompuServe Incorporated. GIF(sm) is a Service Mark pro- perty of CompuServe Incorporated. Kudos to Jef Poskanzer for his excellent PBMPLUS toolkit. AUTHOR Copyright (C) 1989, 1990, 1993 by Kirk Lauritz Johnson. Modified 1993 by Dimitris Evmorfopoulos. MTU Last change: 14 November 1993 3