<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>GRASS GIS: r.contour</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>r.contour</b></em> - Produces a vector map layer of specified contours from a raster map layer. <h2>KEYWORDS</h2> raster <h2>SYNOPSIS</h2> <b>r.contour</b><br> <b>r.contour help</b><br> <b>r.contour</b> [-<b>qn</b>] <b>input</b>=<em>name</em> <b>output</b>=<em>name</em> [<b>levels</b>=<em>float</em>[,<i>float</i>,...]] [<b>minlevel</b>=<em>float</em>] [<b>maxlevel</b>=<em>float</em>] [<b>step</b>=<em>float</em>] [<b>cut</b>=<em>integer</em>] [--<b>overwrite</b>] [--<b>verbose</b>] [--<b>quiet</b>] <h3>Flags:</h3> <DL> <DT><b>-q</b></DT> <DD>Run quietly</DD> <DT><b>-n</b></DT> <DD>Suppress single crossing error messages</DD> <DT><b>--overwrite</b></DT> <DD>Allow output files to overwrite existing files</DD> <DT><b>--verbose</b></DT> <DD>Verbose module output</DD> <DT><b>--quiet</b></DT> <DD>Quiet module output</DD> </DL> <h3>Parameters:</h3> <DL> <DT><b>input</b>=<em>name</em></DT> <DD>Name of input raster map</DD> <DT><b>output</b>=<em>name</em></DT> <DD>Name for output vector map</DD> <DT><b>levels</b>=<em>float[,<i>float</i>,...]</em></DT> <DD>List of contour levels</DD> <DT><b>minlevel</b>=<em>float</em></DT> <DD>Minimum contour level</DD> <DT><b>maxlevel</b>=<em>float</em></DT> <DD>Maximum contour level</DD> <DT><b>step</b>=<em>float</em></DT> <DD>Increment between contour levels</DD> <DT><b>cut</b>=<em>integer</em></DT> <DD>Minimum number of points for a contour line (0 -> no limit)</DD> <DD>Default: <em>0</em></DD> </DL> <h2>DESCRIPTION</h2> <em>r.contour</em> produces a GRASS binary vector map of specified contours from a GRASS raster map. Contours can be produced using a comma-separated list of values in <b>levels</b>, or at some regular increment using the <b>step</b> parameter, using <b>minlevel</b> and <b>maxlevel</b> as minimum and maximum contour values, respectively. If no <b>minlevel</b> or <b>maxlevel</b> is specified, the minimum and maximum cell values in the <b>input</b> raster map will be used. <H2>NOTES</H2> <em>r.contour</em> will either step through incremental contours or produce contours from a list of levels, not both. If both a list of levels and a step are specified, the list will be produced and the step will be ignored. <p>Zero is treated as a valid data value by <em>r.contour</em>. <p>If a contour level exactly matches a category value in the raster map, the contour line may backtrack on itself, causing illegal arcs to be produced in the output GRASS vector map. <p>The optional <b>cut</b> parameter allows the user to specify a minimum number of raster cells eligilble to be included in a contour line written to the <b>output</b> vector map. It acts like a filter, omitting spurs, single points, etc., making the output more generalized. <h2>EXAMPLE</h2> In the Spearfish location, produce a vector contour map from input raster <i>elevation.dem</i> with contour levels from 1000m to 2000m, 100m contour step, and a minimum of 200 input raster points contributing to the contour line: <div><pre class="code"> r.contour input=elevation.dem output=elevation_dem_contours minlevel=1000 maxlevel=2000 step=100 cut=200 </pre></div> <h2>AUTHORS</h2> Terry Baker, U.S. Army Construction Engineering Research Laboratory<br> 3/2001: cut parameter and fixes by Andrea Aime (aaime@libero.it) <p><i>Last changed: $Date: 2008-03-14 14:42:11 +0100 (Fri, 14 Mar 2008) $</i> <HR> <P><a href="index.html">Main index</a> - <a href="raster.html">raster 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>
