<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>GRASS GIS: d.rhumbline</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <link rel="stylesheet" href="grassdocs.css" type="text/css"> </head> <body bgcolor="white"> <img src="grass_logo.png" alt="GRASS logo"><hr align=center size=6 noshade> <h2>NAME</h2> <em><b>d.rhumbline</b></em> - Displays the rhumbline joining two user-specified points, in the active frame on the user's graphics monitor. <h2>KEYWORDS</h2> display <h2>SYNOPSIS</h2> <b>d.rhumbline</b><br> <b>d.rhumbline help</b><br> <b>d.rhumbline</b> [<b>coor</b>=<em>lon1,lat1,lon2,lat2</em>] [<b>lcolor</b>=<em>string</em>] [--<b>verbose</b>] [--<b>quiet</b>] <h3>Parameters:</h3> <DL> <DT><b>coor</b>=<em>lon1,lat1,lon2,lat2</em></DT> <DD>Starting and ending coordinates</DD> <DT><b>lcolor</b>=<em>string</em></DT> <DD>Line color</DD> <DD>Options: <em>red,orange,yellow,green,blue,indigo,violet,white,black,gray,brown,magenta,aqua,grey,cyan,purple</em></DD> <DD>Default: <em>black</em></DD> </DL> <H2>DESCRIPTION</H2> A rhumbline (loxodrome) is a line following a constant angle of the compass (i.e., a line of constant direction). It crosses all meridians at the same angle, i.e. a path of constant bearing. <!-- There are 32 points on the compass (points are roughly 11 degrees 15 minutes apart). --> <EM>d.rhumbline</EM> displays the rhumbline joining any two user-specified points in the active frame on the user's graphics monitor. The named coordinate locations must fall within the boundaries of the user's current geographic region. <P> The user can run this program either interactively or non-interactively. If the user simply types <B>d.rhumbline</B> on the command line and runs it without specifying parameter values, the mouse will be activated and the user will be asked to use the mouse to indicate the two endpoints of the rhumbline. The rhumbline is then drawn in the default color (black). <!-- The program also outputs the coordinate locations of the two endpoints on the user's terminal and the number associated with the mouse button depressed by the user in a format useful for input to other programs. --> <P> Alternately, the user can specify the starting and ending longitude/latitude coordinates of the rhumbline and (optionally) the color in which the rhumbline will be displayed; in this case, the program will run non-interactively. <H2>NOTES</H2> This program works only with longitude-latitude locations. <H2>SEE ALSO</H2> <EM><A HREF="d.geodesic.html">d.geodesic</A></EM> <H2>AUTHOR</H2> Michael Shapiro, U.S. Army Construction Engineering Research Laboratory <p><i>Last changed: $Date: 2005-10-18 09:45:17 +0200 (Tue, 18 Oct 2005) $</i> <HR> <P><a href="index.html">Main index</a> - <a href="display.html">display index</a> - <a href="full_index.html">Full index</a></P> <P>© 2003-2008 <a href="http://grass.osgeo.org">GRASS Development Team</a></p> </body> </html>
