[GRASS-SVN] r58596 - grass/branches/develbranch_6/raster/r.to.vect

[svn_grass at osgeo.org]

Author: neteler
Date: 2014-01-03 10:40:28 -0800 (Fri, 03 Jan 2014)
New Revision: 58596

Modified:
   grass/branches/develbranch_6/raster/r.to.vect/description.html
Log:
r.to.vect manual: examples added

Modified: grass/branches/develbranch_6/raster/r.to.vect/description.html
===================================================================
--- grass/branches/develbranch_6/raster/r.to.vect/description.html	2014-01-03 18:40:22 UTC (rev 58595)
+++ grass/branches/develbranch_6/raster/r.to.vect/description.html	2014-01-03 18:40:28 UTC (rev 58596)
@@ -4,17 +4,16 @@
 layer, extracts points, lines or area edge features from it, converts data
 to GRASS vector format.
 
-<h3>Points</h3>
+<h3>Point conversion</h3>
 
-The <em>r.to.vect</em> program extracts data from a GRASS raster map layer and stores output 
-in a new GRASS <em>vector</em> file.  
+The <em>r.to.vect</em> program extracts data from a GRASS raster map 
+layer and stores output in a new GRASS <em>vector</em> file.  
 
-<h3>Lines</h3>
+<h3>Line conversion</h3>
 <em>r.to.vect</em> assumes that the <em>input</em> map has been thinned
 using <em><a href="r.thin.html">r.thin</a></em>.
 
 <p>
-
 <em>r.to.vect</em> extracts vectors (aka, "arcs") from a
 raster map.  These arcs may represent linear features
 (like roads or streams), or may represent area edge
@@ -22,7 +21,6 @@
 units).  
 
 <p>
-
 <em><a href="r.thin.html">r.thin</a></em> and <em>r.to.vect</em>
 may create excessive nodes at every junction, and may create small spurs
 or "dangling lines" during the thinning and vectorization process.
@@ -30,7 +28,7 @@
 <em><a href="v.clean.html">v.clean</a></em>.
 
 
-<h3>Areas</h3>
+<h3>Area conversion</h3>
 
 <em>r.to.vect</em> first traces the perimeter of each unique
 area in the raster map layer and creates vector data to
@@ -39,10 +37,9 @@
 resultant vector area edge data.
 
 <p>
-
 A true vector tracing of the area edges might appear
 blocky, since the vectors outline the edges of raster data
-that are stored in rectangular cells.  To produce a
+that are stored in rectangular cells. To produce a
 better-looking vector map, <em>r.to.vect</em> smoothes the
 corners of the vector data as they are being extracted. At
 each change in direction (i.e., each corner), the two
@@ -57,30 +54,84 @@
 error introduced by smoothing.
 
 <p>
+<em>r.to.vect</em> extracts only area edges from the named raster 
+input file. If the raster map contains other data (i.e., line edges, 
+or point data) the output may be wrong.
 
-<em>r.to.vect</em> extracts only area edges from the named raster input file. 
-If the raster map contains other data (i.e., line edges, or point data) the
-output may be wrong. 
+<h2>EXAMPLES</h2>
 
+The examples are based on the North Carolina sample dataset:
+<p>
+<b>Conversion of raster points to vector points:</b>
+<p>
+Random sampling of points:
+<div class="code"><pre>
+g.region rast=elevation -p
+# random sampling of points (note that r.random also writes vector points)
+r.random elevation raster_output=elevrand1000 n=1000
+r.to.vect input=elevrand1000 output=elevrand1000 feature=point
+# univariate statistics of sample points
+v.univar elevrand1000 column=value type=point
+# compare to univariate statistics on original full raster map
+r.univar elevation
+</pre></div>
+<p>
+
+<b>Conversion of raster lines to vector lines:</b>
+<p>
+Vectorization of streams in watershed basins map:
+<div class="code"><pre>
+g.region rast=elevation -p
+r.watershed elev=elevation stream=elev.streams thresh=50000
+r.to.vect -s input=elev.streams output=elev_streams feature=line
+# drop "label" column which is superfluous in this example
+v.db.dropcol map=elev_streams column=label
+v.db.renamecol map=elev_streams column=value,basin_id
+# report length per basin ID
+v.report map=elev_streams option=length units=meters 
+</pre></div>
+<p>
+
+<b>Conversion of raster polygons to vector polygons:</b>
+<p>
+Vectorization of simplified landuse class map:
+<div class="code"><pre>
+g.region rast=landclass96 -p
+# we smooth corners of area features
+r.to.vect -s input=landclass96 output=my_landclass96 feature=area
+v.colors my_landclass96 color=random
+# show colorized vector map
+d.mon x0
+d.vect my_landclass96 -a
+</pre></div>
+
 <h2>BUGS</h2>
 
 For feature=line the input raster map MUST be thinned by
 <em><a href="r.thin.html">r.thin</a></em>;
 if not, <em>r.to.vect</em> may crash.
 
-<h2>AUTHOR</h2>
-<b>Points</b><br>
+<h2>SEE ALSO</h2>
+
+<em>
+<a href="g.region.html">g.region</a>,
+<a href="r.thin.html">r.thin</a>,
+<a href="v.clean.html">v.clean</a>
+</em>
+
+<h2>AUTHORS</h2>
+<b>Point support</b><br>
 Bill Brown<br>
 <br>
 
-<b>Lines</b><br>
+<b>Line support</b><br>
 Mike Baba<br>
 DBA Systems, Inc.<br>
 10560 Arrowhead Drive<br>
 Fairfax, Virginia 22030<br>
 <br>
 
-<b>Areas</b><br>
+<b>Area support</b><br>
 <em>Original</em> version of <em>r.poly</em>: 
 <br>
 Jean Ezell and Andrew Heekin,