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-<h2>DESCRIPTION</h2>
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-<em>r.grow.distance</em> generates a raster map representing the
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-distance to the nearest non-null cell in the input map.
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-
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-<h2>NOTES</h2>
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-The user has the option of specifying four different metrics which
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-control the geometry in which grown cells are created, (controlled by
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-the <b>metric</b> parameter): <i>Euclidean</i>, <i>Squared</i>,
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-<i>Manhattan</i>, and <i>Maximum</i>.
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-
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-<p>
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-
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-The <i>Euclidean distance</i> or <i>Euclidean metric</i> is the "ordinary" distance
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-between two points that one would measure with a ruler, which can be
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-proven by repeated application of the Pythagorean theorem.
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-The formula is given by:
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-
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-<div class="code"><pre>d(dx,dy) = sqrt(dx^2 + dy^2)</pre></div>
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-
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-Cells grown using this metric would form isolines of distance that are
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-circular from a given point, with the distance given by the <b>radius</b>.
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-
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-<p>
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-The <i>Squared</i> metric is the <i>Euclidean</i> distance squared,
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-i.e. it simply omits the square-root calculation. This may be faster,
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-and is sufficient if only relative values are required.
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-
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-<p>
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-
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-The <i>Manhattan metric</i>, or <i>Taxicab geometry</i>, is a form of geometry in
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-which the usual metric of Euclidean geometry is replaced by a new
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-metric in which the distance between two points is the sum of the (absolute)
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-differences of their coordinates. The name alludes to the grid layout of
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-most streets on the island of Manhattan, which causes the shortest path a
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-car could take between two points in the city to have length equal to the
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-points' distance in taxicab geometry.
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-The formula is given by:
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-
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-<div class="code"><pre>d(dx,dy) = abs(dx) + abs(dy)</pre></div>
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-
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-where cells grown using this metric would form isolines of distance that are
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-rhombus-shaped from a given point.
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-
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-<p>
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-
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-The <i>Maximum metric</i> is given by the formula
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-
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-<div class="code"><pre>d(dx,dy) = max(abs(dx),abs(dy))</pre></div>
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-
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-where the isolines of distance from a point are squares.
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-
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-
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-<h2>EXAMPLE</h2>
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-
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-Spearfish sample dataset
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-<div class="code"><pre>
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-r.grow.distance in=roads out=dist_from_roads
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-</pre></div>
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-
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-<h2>SEE ALSO</h2>
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-
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-<em>
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-<a href="r.grow.html">r.grow</a><br>
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-<a href="r.buffer.html">r.buffer</a><br>
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-<a href="r.cost.html">r.cost</a><br>
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-<a href="r.patch.html">r.patch</a>
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-</em>
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-
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-<p>
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-
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-<em>
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-<a href="http://en.wikipedia.org/wiki/Euclidean_metric">Wikipedia Entry:
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- Euclidean Metric</a><br>
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-<a href="http://en.wikipedia.org/wiki/Manhattan_metric">Wikipedia Entry:
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- Manhattan Metric</a>
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-</em>
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-
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-<h2>AUTHORS</h2>
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-
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-Glynn Clements
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-
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-<p>
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-<i>Last changed: $Date$</i>
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Hamish Bowman