v.mkgrid manual: point pattern example added

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@62816 15284696-431f-4ddb-bdfa-cd5b030d7da7

vector/v.mkgrid/v.mkgrid.html

@@ -8,14 +8,17 @@ Both point and area vector grids can be created.
 
 Grid points created with the <b>-p</b> flag will be placed at the
 <i>center</i> of each grid cell, not at the grid line nodes.
-<p>This is NOT to be used to generate a vector map of USGS quadrangles,
+
+<p>
+This is NOT to be used to generate a vector map of USGS quadrangles,
 because USGS quads are not exact rectangles.
 
 
 <h2>EXAMPLES</h2>
 
-1) Create a grid in a latitude-longitude location (WGS84):
+<h3>Creating a global grid in a latitude-longitude</h3>
 
+To be run in a latitude-longitude location (WGS84)
 <div class="code"><pre>
 # use g.region to easily calculate rows and column for 'grid':
 g.region n=90 s=-90 w=-180 e=180 res=10 -p
@@ -37,29 +40,44 @@ cells:      648
 v.mkgrid map=grid_10deg grid=18,36
 </pre></div>
 
-<p>
-2) Make a 4x3 grid, cells 20km a side, with lower left corner at 2716500,6447000:
+<h3>Creating a grid in a metric projection</h3>
+
+Creating a 4x3 grid, cells 20km a side, with lower left corner at 2716500,6447000:
+
 <div class="code"><pre>
 v.mkgrid map=coro_grid grid=4,3 position=coor coor=2716500,6447000 box=20000,20000
 </pre></div>
 
-<p>
-3) Make a 10x12 lat/lon grid, cells 2 arc-min a side, with lower left corner
+<h3>Creating a positioned grid in a latitude-longitude</h3>
+
+Creating a 10x12 lat/lon grid, cells 2 arc-min a side, with lower left corner
 at 167deg 52min east, 47deg 6min south. For use with e.g. QGIS you can then
 pull this grid into a projected location with <em>v.proj</em> before
-exporting as a Shapefile with <em>v.out.ogr</em> (within GRASS you could
+exporting as a Shapefile with <em>v.out.ogr</em> (within GRASS GIS you could
 just use <em>d.grid -w</em> from the projected location for the same effect):
 
 <div class="code"><pre>
 v.mkgrid map=p2min_grid grid=10,12 position=coor coor=167:52E,47:06S box=0:02,0:02
 </pre></div>
 
+<h3>Creating a point pattern</h3>
+
+North Carolina sample dataset example, creating a 1km spaced point grid
+based on the current region extent defined by the "elevation" map:
+
+<div class="code"><pre>
+g.region rast=elevation -p
+# we use the row/column/resolution information to determine the grid= values:
+v.mkgrid -p map=pointpattern grid=13,15 position=region breaks=1
+</pre></div>
+
 
 <h2>SEE ALSO</h2>
 
 <em>
-<a href="v.patch.html">v.patch</a>,
-<a href="d.grid.html">d.grid</a>
+<a href="d.grid.html">d.grid</a>,
+<a href="v.in.region.html">v.in.region</a>,
+<a href="v.patch.html">v.patch</a>
 </em>
 
 <h2>AUTHORS</h2>