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@@ -1,10 +1,16 @@
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<h2>DESCRIPTION</h2>
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-<em>r.contour</em> produces a GRASS binary vector map of specified contours from a GRASS raster map.
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+<em>r.contour</em> produces a vector map of specified contours from input raster map.
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-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.
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+Contours can be produced using a comma-separated list of values
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+in <b>levels</b>, or at some regular increment using the <b>step</b>
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+parameter, using <b>minlevel</b> and <b>maxlevel</b> as minimum and
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+maximum contour values, respectively. If no <b>minlevel</b>
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+or <b>maxlevel</b> is specified, the minimum and maximum cell values
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+in the <b>input</b> raster map will be used.
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<h2>NOTES</h2>
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+
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<em>r.contour</em> will either step through incremental contours or produce
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contours from a list of levels, not both. If both a list of levels and
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a step are specified, the list will be produced and the step will be ignored.
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@@ -13,24 +19,27 @@ a step are specified, the list will be produced and the step will be ignored.
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<p>If a contour level exactly matches a category value in the raster map,
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the contour line may backtrack on itself, causing illegal arcs to be produced
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-in the output GRASS vector map.
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+in the output vector map.
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<p>The optional <b>cut</b> parameter allows the user to specify a minimum number of
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raster cells eligilble to be included in a contour line written to the <b>output</b>
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vector map. It acts like a filter, omitting spurs, single points, etc., making the output more generalized.
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<h2>EXAMPLE</h2>
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+
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In the Spearfish location, produce a vector contour map from input raster <i>elevation.dem</i>
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with contour levels from 1000m to 2000m, 100m contour step, and a minimum of 200 input raster
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points contributing to the contour line:
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-<div><pre class="code">
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+<div class="code"><pre>
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r.contour input=elevation.dem output=elevation_dem_contours minlevel=1000 maxlevel=2000 step=100 cut=200
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</pre></div>
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<h2>AUTHORS</h2>
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+
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Terry Baker, U.S. Army Construction Engineering Research Laboratory<br>
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3/2001: cut parameter and fixes by Andrea Aime (aaime@libero.it)
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-<p><i>Last changed: $Date$</i>
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+<p>
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+<i>Last changed: $Date$</i>
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Martin Landa