Geografic-Information-System/scripts/r.shade/r.shade.html

<h2>DESCRIPTION</h2>

<em>r.shade</em> will drape a color raster map over a shaded relief map.
In place of shaded relief, any raster map can be used including aspect or slope.
The color raster map is usually an elevation raster map with colorful color
table (as opposed to gray scale color table). However, any raster map can be
used including categorical raster maps.
The result is a raster map created from elevation and the shade raster.

<p>
Comparing to creating shaded relief as semi-transparent overlay on
the color raster map, this module gives result with more saturated colors.

<p>
The input for this module can be created for example using
<em><a href="r.slope.aspect.html">r.slope.aspect</a></em> or
<em><a href="r.relief.html">r.relief</a></em>.

<p>
NULL values are propagated by default, so if any of the two input rasters
contains NULL cell NULL will be also in the output. If <b>-c</b> flag is
used and cell in <b>color</b> raster is NULL, just <b>shade</b>
color is used. If cell in <b>shade</b> raster is NULL, shading effect
is not applied and original colors are used. If <b>bgcolor</b> option is
used, NULL value in any input raster will be in the output replaced
by the given color.


<h2>NOTES</h2>

Refer to the <em><a href="r.his.html">r.his</a></em> help page for more details;
<em>r.shade</em> is a frontend to that module with addition of
brightness support similar to one provided by
<em><a href="d.shade.html">d.shade</a></em>.
However, note that the brightness is not implemenented in the same way as for
<em><a href="d.shade.html">d.shade</a></em> and the results might
be different.
<em>r.shade</em> is using method described in <em><a href="r.his.html">r.his</a></em>
manual page.


<h2>EXAMPLES</h2>

In this example, the <tt>aspect</tt> map in the North Carolina sample
dataset location is used to hillshade the <tt>elevation</tt> map:

<div class="code"><pre>
g.region raster=aspect -p
r.shade shade=aspect color=elevation output=elevation_aspect_shaded

d.mon wx0
d.rast elevation_aspect_shaded
</pre></div>

In this next example, a shaded relief raster map is created
and used to create a colorized hillshade
raster map for later use:

<div class="code"><pre>
g.region raster=elevation
r.relief input=elevation output=elevation_shaded_relief

r.shade shade=elevation_shaded_relief color=elevation \
    output=elevation_relief_shaded

d.mon wx1
d.rast elevation_relief_shaded
</pre></div>

Interesting visualizations can be created using different color tables for
elevation raster map, for example using <tt>haxby</tt> color table.

<!--
image generated using the example above
display region: g.region -a n=227228 s=220895 w=631362 e=641170
d.out.file rshade.png
optipng -o5 rshade.png
Note: The image is darker in the GNOME image viewer than the one in the map
display. However, Firefox shows the same colors.
-->
<center>
<img src="rshade.png" alt="Elevation with shaded relief (hillshade)">
<p>
Figure: A detail of raster created by applying shading effect of shaded relief
(hillshade) to elevation raster map from North Carolina dataset elevation map
</center>


<h2>SEE ALSO</h2>

<em>
<a href="r.his.html">r.his</a>,
<a href="d.his.html">d.his</a>,
<a href="d.shade.html">d.shade</a>,
<a href="g.pnmcomp.html">g.pnmcomp</a>,
<a href="r.slope.aspect.html">r.slope.aspect</a>,
<a href="r.relief.html">r.relief</a>
</em>


<h2>AUTHORS</h2>

Hamish Bowman<br>
Vaclav Petras, <a href="http://geospatial.ncsu.edu/osgeorel/">NCSU OSGeoREL</a><br>
Inspired by <em><a href="d.shade.html">d.shade</a></em> and
manual for <em><a href="r.his.html">r.his</a></em>.

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