[GRASS-SVN] r56188 - grass-addons/grass6/raster/r.viewshed.cva

[svn_grass at osgeo.org]

Author: neteler
Date: 2013-05-10 11:32:44 -0700 (Fri, 10 May 2013)
New Revision: 56188

Modified:
   grass-addons/grass6/raster/r.viewshed.cva/description.html
Log:
r.viewshed.cva: HTML cleanup

Modified: grass-addons/grass6/raster/r.viewshed.cva/description.html
===================================================================
--- grass-addons/grass6/raster/r.viewshed.cva/description.html	2013-05-10 13:02:31 UTC (rev 56187)
+++ grass-addons/grass6/raster/r.viewshed.cva/description.html	2013-05-10 18:32:44 UTC (rev 56188)
@@ -1,25 +1,95 @@
 <h2>DESCRIPTION</h2>
 
-<p><em>r.viewshed.cva</em> is a module that allows for the construction of "Cumulative Viewshed", or "visualscape" maps from a series of input points stored in a vector points map. The routine is a python wrapper script that iterative loops through each input point, calculating a viewshed map, and then creates an output map that is coded by the number of input locations that can "see" each cell. <em>r.viewshed.cva</em> uses the GRASS addon <em>r.viewshed</em> for the viewshed analysis (instead of the standard module <span style="font-style: italic;">r.los</span>) because <span style="font-style: italic;">r.viewshed</span> is substantially faster, thus allowing for a cumulative viewshed analysis to run in a reasonable amount of time. The final cumulative viewshed map is computed using the "count" method of <span style="font-style: italic;">r.series</span>, rather than with mapcalc, as it better handles the null values in the individual constituent viewshed maps (and allows fo
 r interim viewshed maps to be coded in any way)
+<em>r.viewshed.cva</em> is a module that allows for the 
+construction of "Cumulative Viewshed", or "visualscape" maps from a 
+series of input points stored in a vector points map. The routine is 
+a python wrapper script that iterative loops through each input 
+point, calculating a viewshed map, and then creates an output map 
+that is coded by the number of input locations that can "see" each 
+cell. <em>r.viewshed.cva</em> uses the GRASS addon <em>r.viewshed</em>
+for the viewshed analysis (instead of the standard module <it>r.los</it>)
+because <it>r.viewshed</it> is substantially faster, 
+thus allowing for a cumulative viewshed analysis to run in a 
+reasonable amount of time. The final cumulative viewshed map is 
+computed using the "count" method of <it>r.series</it>, rather than 
+with mapcalc, as it better handles the null values in the individual 
+constituent viewshed maps (and allows for interim viewshed maps to 
+be coded in any way)
 
-</p><h3>Options and flags:</h3> <span style="font-style: italic;">r.viewshed.cva</span> requires an input elevation map and an input vector points map with at least three columns of data: one contains a unique identifier for each point (e.g., "cat"), one contains the easting of the point, and one contains the northing of the point. There<em></em> is currently only one native flag for <span style="font-style: italic;">r.viewshed.cva</span> (-k), which allows you to keep the interim viewshed maps made for each input point. All other flags and options are inherited from r.viewshed (see the<span style="font-style: italic;"> r.viewshed</span> help page for more information on these)<span style="font-weight: bold;"><br><br></span><h2>NOTES</h2>The input vector points map can be manually digitized (with <span style="font-style: italic;">v.digit</span>) over topographic or cultural features, or can be created as a series of random points (with <span style="font-style: italic;">r.ran
 dom</span> or <span style="font-style: italic;">v.random</span>). The required "name_column" can be any alpha numeric value, as long as it is unique for each input point. The required "x_column" and "y_column" columns can be added with <span style="font-style: italic;">v.db.addcol</span>, and the eastings and northings uploaded to these columns with <span style="font-style: italic;">v.to.db</span>. Note that using the flag -k allows you to keep any interim viewshed maps created during the analysis. This is also useful for simple creating a large number of individual viewsheds from points in a vector file. <br><br>Also note that you must first install the GRASS addon <span style="font-style: italic;">r.viewshed</span> before you can use this module. <span style="font-style: italic;">r.viewshed</span> offers several significant advnatages over <span style="font-style: italic;">r.los</span>, not least a great increase in processing speed. Use of<span style="font-style: italic;"
 > r.los</span> would mean that only a small number of input points could be used. Use of <span style="font-style: italic;">r.viewshed</span> means that a much larger number of points could be used (trials showed that viewsheds were calculated for 100 input points in about 1.5 hrs at a 10m resolution for a region spanning some 40km by 10km).<br><h2>EXAMPLES</h2>
+<h3>Options and flags:</h3>
+
+<it>r.viewshed.cva</it> requires an input elevation map and an input 
+vector points map with at least three columns of data: one contains 
+a unique identifier for each point (e.g., "cat"), one contains the 
+easting of the point, and one contains the northing of the point. 
+There is currently only one native flag for <it>r.viewshed.cva</it> 
+(-k), which allows you to keep the interim viewshed maps made for 
+each input point. All other flags and options are inherited from 
+r.viewshed (see the<it> r.viewshed</it> help page for more 
+information on these).
+
+<h2>NOTES</h2>
+
+The input vector points map can be manually digitized (with <it>
+v.digit</it>) over topographic or cultural features, or can be 
+created as a series of random points (with <it>r.random</it> or <it>
+v.random</it>). The required "name_column" can be any alpha numeric 
+value, as long as it is unique for each input point. The required 
+"x_column" and "y_column" columns can be added with <it>v.db.addcol</it>,
+and the eastings and northings uploaded to these columns with 
+<it>v.to.db</it>. Note that using the flag -k allows you to keep any 
+interim viewshed maps created during the analysis. This is also 
+useful for simple creating a large number of individual viewsheds 
+from points in a vector file.
+
+<p>
+	
+Also note that you must first install the GRASS addon <it>r.viewshed
+</it> before you can use this module. <it>r.viewshed</it> offers 
+several significant advnatages over <it>r.los</it>, not least a 
+great increase in processing speed. Use of <it>r.los</it> would mean 
+that only a small number of input points could be used. Use of
+<it>r.viewshed</it> means that a much larger number of points could be 
+used (trials showed that viewsheds were calculated for 100 input 
+points in about 1.5 hrs at a 10m resolution for a region spanning 
+some 40km by 10km).
+
+<h2>EXAMPLES</h2>
 Undertake a cumulative viewshed analysis from a digitized vector points map of prominent peaks in a region:<br>
 
-<div class="code"><pre>g.region rast=elevation_10m_dem at PERMANENT<br>v.db.addcol map=prominent_peaks_points at PERMANENT columns=x double, y double<br>v.to.db map=prominent_peaks_points at PERMANENT option=coor columns=x,y<br>r.viewshed.cva.py elev=elevation10m_demPERMANENT output=peaks_CVA_map vect=prominent_peaks_points at PERMANENT x_column=x y_column=y name_column=cat obs_elev=0.0 tgt_elev=1.75 max_dist=-1 mem=1500<br><br></pre></div>
+<div class="code"><pre>
+g.region rast=elevation_10m_dem at PERMANENT -p
+v.db.addcol map=prominent_peaks_points at PERMANENT columns=x double, y double
+v.to.db map=prominent_peaks_points at PERMANENT option=coor columns=x,y
+r.viewshed.cva.py elev=elevation10m_demPERMANENT output=peaks_CVA_map \
+  vect=prominent_peaks_points at PERMANENT x_column=x y_column=y \
+  name_column=cat obs_elev=0.0 tgt_elev=1.75 max_dist=-1 mem=1500
+</pre></div>
 
 
-<br>Undertake a cumulative viewshed analysis from a 10% sample of landscape locations in a region:<br><pre>g.region rast=elevation_10m_dem at PERMANENT<br>r.random input=elevation10m_demPERMANENT n=10% vector_output=rand_points_10p<br>v.db.addcol map=rand_points_10p at PERMANENT columns=x double, y double<br>v.to.db map=rand_points_10p at PERMANENT option=coor columns=x,y<br>r.viewshed.cva.py elev=elevation10m_demPERMANENT output=peaks_CVA_map vect=rand_points_10p at PERMANENT x_column=x y_column=y name_column=cat obs_elev=0.0 tgt_elev=1.75 max_dist=-1 mem=1500<br></pre><br>
+<br>Undertake a cumulative viewshed analysis from a 10% sample of landscape locations in a region:<br>
 
+<div class="code"><pre>
+g.region rast=elevation_10m_dem at PERMANENT
+r.random input=elevation10m_demPERMANENT n=10% vector_output=rand_points_10p
+v.db.addcol map=rand_points_10p at PERMANENT columns=x double, y double
+v.to.db map=rand_points_10p at PERMANENT option=coor columns=x,y
+r.viewshed.cva.py elev=elevation10m_demPERMANENT output=peaks_CVA_map \
+  vect=rand_points_10p at PERMANENT x_column=x y_column=y \
+  name_column=cat obs_elev=0.0 tgt_elev=1.75 max_dist=-1 mem=1500
+</pre></div>
 
+
 <h2>SEE ALSO</h2>
 
 <em>
-<a href="r.viewshed.html">r.viewshed</a><br>
+<a href="r.viewshed.html">r.viewshed</a>
 </em>
 
 
-<h2>AUTHOR</h2>Isaac Ullah<i><br><br></i>
+<h2>AUTHOR</h2>
 
+Isaac Ullah
+
 <p>
 <i>Last changed: $Date: 2013-05-09 00:47:10 -0500 (Thurs, 09 May 2013) $</i>
-</p>
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