NAME

       d.geodesic   -  Displays  a  geodesic  line,  tracing  the  shortest  distance between two
       geographic points along a great circle, in a longitude/latitude data set.

KEYWORDS

       display, distance

SYNOPSIS

       d.geodesic
       d.geodesic help
       d.geodesic  [coor=lon1,lat1,lon2,lat2]   [lcolor=string]    [tcolor=string]    [--verbose]
       [--quiet]

   Parameters:
       coor=lon1,lat1,lon2,lat2
           Starting and ending coordinates

       lcolor=string
           Line color
           Options:
           red,orange,yellow,green,blue,indigo,violet,white,black,gray,brown,magenta,aqua,grey,cyan,purple
           Default: black

       tcolor=string
           Text color or "none"

DESCRIPTION

       d.geodesic  displays  a  geodesic line in the active frame on the user's graphics monitor.
       This is also known as the great circle line and traces the shortest distance  between  two
       user-specified  points  on  the  curved  surface of a longitude/latitude data set. The two
       coordinate locations  named  must  fall  within  the  boundaries  of  the  user's  current
       geographic region.

OPTIONS

       This  program  can  be  run  either interactively or non-interactively.  If the user types
       d.geodesic on the command line and runs it without other  program  parameters,  the  mouse
       will  be activated; the user is asked to use the mouse to indicate the starting and ending
       points of each geodesic line to be drawn. The default line color (black)  and  text  color
       (red) will be used.

       Alternately,  the  user  can  specify the starting and ending coordinates of the geodesic,
       line color, and text color on the command line, and run the program non-interactively.

       Once the user indicates the starting and ending coordinates of the geodesic, the line  and
       its  length  (in miles) are displayed to the user's graphics monitor. If the text color is
       set to none, the great circle distance is not displayed.

EXAMPLE

       g.region vect=world_political -p
       d.mon wx0
       d.vect world_political type=area
       d.geodesic coor=55:58W,33:18S,26:43E,60:37N lcolor=red tcolor=violet

       Geodesic line (great circle line)

NOTES

       This program works only with GRASS locations using a longitude/latitude coordinate system.

SEE ALSO

       d.rhumbline

AUTHOR

       Michael Shapiro, U.S. Army Construction Engineering Research Laboratory

       Last changed: $Date: 2011-11-08 03:29:50 -0800 (Tue, 08 Nov 2011) $

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       © 2003-2013 GRASS Development Team