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@@ -5,6 +5,9 @@ user-specified raster map layer. The module calculates textural features
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based on spatial dependence matrices at 0, 45, 90, and 135
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degrees for a <em>distance</em> (default = 1).
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<p>
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+<em>r.texture</em> assumes grey levels ranging from 0 to 255 as input.
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+The input is rescaled to 0 to 255 if needed.
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+<p>
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In general, several variables constitute texture: differences in grey level values,
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coarseness as scale of grey level differences, presence or lack of directionality
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and regular patterns.
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@@ -94,7 +97,12 @@ Calculation of Angular Second Moment of B/W orthophoto (North Carolina data set)
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<div class="code"><pre>
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g.region rast=ortho_2001_t792_1m -p
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-r.texture -a ortho_2001_t792_1m prefix=ortho_texture
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+# set grey level color table 0% black 100% white
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+r.colors ortho_2001_t792_1m color=grey
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+# extract grey levels
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+r.mapcalc "ortho_2001_t792_1m.greylevel = #ortho_2001_t792_1m"
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+# texture analysis
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+r.texture ortho_2001_t792_1m.greylevel prefix=ortho_texture -a
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# display
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g.region n=221461 s=221094 w=638279 e=638694
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d.shadedmap drape=ortho_texture_ASM_0 rel=ortho_2001_t792_1m
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