r.northerness.easterness.html

<h2>DESCRIPTION</h2>

<p>
<em>r.northerness.easterness</em> calculates northerness, easterness and 
the interaction between northerness and slope (northerness*slope). The 
user must specify the input <b>elevation raster</b> map.
</p>

<h2>NOTES</h2>

<p>
As aspect is a circular land-surface parameter, in ecology a sine or 
cosine transformation is often used to obtain a continuous gradient, 
stressing the north-south or east-west gradient (northness or eastness).
</p>

<p>
The GRASS GIS default aspect angles (cartesian) are converted to compass 
angles. 
</p>

<p>
Calculated raster maps are:
</p>

<ul>
 <li>northerness: <em>cos(aspect)</em></li>
 <li>easterness: <em>sin(aspect)</em></li>
 <li>interaction between northerness and slope: <em>northerness*slope</em></li>
</ul>

<p>
The color of these raster maps are set to <em>grey</em>.
</p>

<h2>EXAMPLE</h2>

<div class="code">
 <pre>
  # align region to DEM and habitat vector
  g.region -a raster=DEM align=DEM

  # run <em>r.northerness.easterness</em>
  r.northerness.easterness elevation=DEM
 </pre>
</div>

<h2>SEE ALSO</h2>

<em>
<a href="r.mapcalc.html">r.mapcalc</a>,
<a href="r.slope.aspect.html">r.slope.aspect</a>
</em>

<h2>REFERENCES</h2>

Olaya, V. 2009. Basic Land-Surface Parameters. In: Hengl, T. & Reuter, 
H.I. (eds.) 2009. Geomorphometry. Concepts, Software, Applications. 
Developments in Soil Science, Volume 33. Elsevier.

<h2>AUTHOR</h2>

Helmut Kudrnovsky

<p>
<i>Last changed: $Date: 2014-12-27 14:30:46 +0100 (Sa., 27 Dez 2014) $</i>
</p>