[GRASS-SVN] r56768 - grass/trunk/misc/m.cogo

[svn_grass at osgeo.org]

Author: hamish
Date: 2013-06-17 23:52:54 -0700 (Mon, 17 Jun 2013)
New Revision: 56768

Modified:
   grass/trunk/misc/m.cogo/m.cogo.html
Log:
add an example of how to build the results into an area (#1144)

Modified: grass/trunk/misc/m.cogo/m.cogo.html
===================================================================
--- grass/trunk/misc/m.cogo/m.cogo.html	2013-06-18 06:08:37 UTC (rev 56767)
+++ grass/trunk/misc/m.cogo/m.cogo.html	2013-06-18 06:52:54 UTC (rev 56768)
@@ -4,7 +4,8 @@
 and X,Y coordinates.  Only simple bearing/distance or coordinate
 pairs are handled. It assumes a cartesian coordinate system.
 
-<p>Input can be entered via standard input (default) or from the file
+<p>
+Input can be entered via standard input (default) or from the file
 <b>input=</b><em>name</em>. Specifying the input as "-" also
 specifies standard input, and is useful for using the program in
 a pipeline.  Output will be to standard output unless a file
@@ -12,14 +13,16 @@
 closely adhere to the following format, where up to a 10 character
 label is allowed but not required (see <b>-l</b> flag).
 
-<p><b>Example COGO input:</b>
+<p>
+<b>Example COGO input:</b>
 <div class="code"><pre>
    P23 N 23:14:12 W 340
    P24 S 04:18:56 E 230
    ...
 </pre></div>
 
-<p>The first column may contain a label and you must use the <b>-l</b>
+<p>
+The first column may contain a label and you must use the <b>-l</b>
 flag so the program knows.  This is followed by a space, and then
 either the character 'N' or 'S' to indicate whether the bearing is
 relative to the north or south directions.  After another space,
@@ -30,22 +33,28 @@
 characters. A space separates the bearing from the distance (which should
 be in appropriate linear units).
 
-<p><b>Output of the above input:</b>
+<p>
+<b>Output of the above input:</b>
 <div class="code"><pre>
    -134.140211 312.420236 P23
    -116.832837 83.072345 P24
    ...
 </pre></div>
-<p>Unless specified with the <b>coord</b> option, calculations begin from (0,0).
 
-<p>For those unfamiliar with the notation for bearings: Picture yourself in the
+<p>
+Unless specified with the <b>coord</b> option, calculations begin from (0,0).
+
+
+<h2>NOTES</h2>
+
+For those unfamiliar with the notation for bearings: Picture yourself in the
 center of a circle.  The first hemispere notation tell you whether you should
 face north or south.  Then you read the angle and either turn that many
 degrees to the east or west, depending on the second hemisphere notation.  
 Finally, you move <distance> units in that direction to get to the 
 next station.
 
-
+<p>
 <em>m.cogo</em> can be run either non-interactively or
 interactively.  The program will be run non-interactively
 if the user specifies any parameter or flag. Use "m.cogo -",
@@ -54,8 +63,6 @@
 using the familiar GRASS parser interface.
 
 <p>
-<h2>NOTES</h2>
-
 This program is very simplistic, and will not handle deviations
 from the input format explained above.  Currently, the
 program doesn't do anything particularly useful with
@@ -63,9 +70,14 @@
 will be extended to provide the capability to generate
 vector and/or sites layers.
 
+<p>
+Lines may be closed by using the <b>-c</b> flag or snapped with
+<em>v.clean</em>, lines may be converted to boundaries with <em>v.type</em>,
+and closed boundaries may be converted to areas with <em>v.centroids</em>.
 
-<h2>EXAMPLE</h2>
 
+<h2>EXAMPLES</h2>
+
 <div class="code"><pre>
    m.cogo -l in=cogo.dat
 </pre></div>
@@ -92,32 +104,43 @@
 P016 S 88:44:56 W 18.7164
 </pre></div>
 
+<p>
 Round trip:
 <div class="code"><pre>
    m.cogo -l in=cogo.dat | m.cogo -rl in="-"
 </pre></div>
 
-
+<p>
 Import as a vector points map:
 <div class="code"><pre>
    m.cogo -l in=cogo.dat | v.in.ascii out=cogo_points x=1 y=2 separator=space
 </pre></div>
 
-
+<p>
 Shell script to import as a vector line map:
 <div class="code"><pre>
-    m.cogo -l in=cogo.dat | tac | awk '
+   m.cogo -l in=cogo.dat | tac | awk '
        BEGIN { FS=" " ; R=0 }
        $1~/\d*\.\d*/ { printf(" %.8f %.8f\n", $1, $2) ; ++R }
        END { printf("L %d\n", R) }' | tac | \
        v.in.ascii -n format=standard out=cogo_line
 </pre></div>
 
-Lines may be closed by using the <b>-c</b> flag or snapped with
-<em>v.clean</em>, lines may be converted to boundaries with <em>v.type</em>,
-and closed boundaries may be converted to areas with <em>v.centroids</em>.
+<p>
+Convert that lines map into an area:
+<div class="code"><pre>
+   # Add the -c flag to the above example to close the loop:
+   m.cogo -l -c in=cogo.dat | ...
+       ...
+   v.type input=cogo_line output=cogo_boundary from_type=line to_type=boundary
+   v.centroids in=cogo_boundary out=cogo_area
+</pre></div>
 
+If necessary, snap the boundary closed with the <em>v.clean</em> module.
+Use <tt>tool=snap</tt> and <tt>thresh=0.0001</tt>, or some small value.
+<!-- does that need a cat number on the boundary to work? -->
 
+
 <h2>SEE ALSO</h2>
 
 <em>
@@ -133,4 +156,5 @@
 
 Eric G. Miller
 
-<p><i>Last changed: $Date$</i>
+<p>
+<i>Last changed: $Date$</i>