3
The <em>r.rescale</em> program rescales the range of
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category values appearing in a raster map layer. A new
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raster map layer, and an appropriate category file and
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color table based upon the original raster map layer, are
7
generated with category labels that reflect the original
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category values that produced each category. This command
9
is useful for producing representations with a reduced
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number of categories from a raster map layer with a large
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range of category values (e.g., elevation).
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<em>Rescaled</em> map layers are appropriate for use in
13
such GRASS programs as
15
<em><a href="r.stats.html">r.stats</a></em>,
16
<em><a href="r.report.html">r.report</a></em>, and
17
<em><a href="r.coin.html">r.coin</a></em>.
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To rescale an elevation raster map layer with category
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values ranging from 1090 meters to 1800 meters into the
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range 0-255, the following command line could be used
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(without the <em>from</em> parameter, the full value range will
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<div class="code"><pre>
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r.rescale input=elevation from=1090,1800 output=elevation.255 to=0,255
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Category values that fall beyond the input range will
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become NULL. This allows the user to select a subset of
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the full category value range for rescaling if desired.
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This also means that the user should know the category
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value range for the input raster map layer. The user can
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request the </b><em>r.rescale</em> program to determine
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this range, or can obtain it using the
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<em><a href="r.describe.html">r.describe</a></em> or <em><a href="r.info.html">r.info</a></em>
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command. If the category value range is determined using
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<em>r.rescale</em>, the input raster map layer is examined,
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and the minimum and maximum non-NULL category values are
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selected as the input range.
48
<em><a href="r.coin.html">r.coin</a></em>,
49
<em><a href="r.describe.html">r.describe</a></em>,
50
<em><a href="r.info.html">r.info</a></em>,
51
<em><a href="r.mapcalc.html">r.mapcalc</a></em>,
52
<em><a href="r.reclass.html">r.reclass</a></em>,
53
<em><a href="r.rescale.eq.html">r.rescale.eq</a></em>,
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<em><a href="r.report.html">r.report</a></em>,
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<em><a href="r.resample.html">r.resample</a></em>,
56
<em><a href="r.stats.html">r.stats</a></em>
60
U.S.Army Construction Engineering Research Laboratory
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<p><i>Last changed: $Date: 2010-10-06 18:11:45 +0200 (Wed, 06 Oct 2010) $</i>