[GRASS-SVN] r62906 - grass/branches/releasebranch_7_0/vector/v.mkgrid

[svn_grass at osgeo.org]

Author: mmetz
Date: 2014-11-25 00:17:40 -0800 (Tue, 25 Nov 2014)
New Revision: 62906

Modified:
   grass/branches/releasebranch_7_0/vector/v.mkgrid/v.mkgrid.html
Log:
v.mkgrid: update examples

Modified: grass/branches/releasebranch_7_0/vector/v.mkgrid/v.mkgrid.html
===================================================================
--- grass/branches/releasebranch_7_0/vector/v.mkgrid/v.mkgrid.html	2014-11-25 08:17:33 UTC (rev 62905)
+++ grass/branches/releasebranch_7_0/vector/v.mkgrid/v.mkgrid.html	2014-11-25 08:17:40 UTC (rev 62906)
@@ -27,8 +27,9 @@
 
 <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
@@ -50,29 +51,70 @@
 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 simple 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 type=point map=pointpattern grid=13,15 position=region breaks=1
+</pre></div>
+<p>
+
+<h3>Creating a regular point pattern</h3>
+
+North Carolina sample dataset example, creating a regular spaced point grid
+based on the current region extent defined by the "elevation" map, using
+a two-step approach:
+
+<div class="code"><pre>
+# create first set of points, covering extent of "elevation" raster map
+g.region rast=elevation -p
+v.mkgrid type=point map=pointpattern1 grid=13,15 position=region breaks=1
+
+# shift grid by half point distance (map units)
+g.region n=n+500 w=w+500 e=e+500 s=s+500 -p
+
+# create second set of points
+v.mkgrid type=point map=pointpattern2 grid=13,15 position=region breaks=1
+
+# merge into final point pattern
+v.patch input=pointpattern1,pointpattern2 output=pointpattern3
+</pre></div>
+
+<center>
+<img src="v_mkgrid_ppattern.png"><br>
+Different point patterns for sampling design
+</center>
+
 <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>