[GRASS-SVN] r56385 - grass/trunk/vector/v.net.path

[svn_grass at osgeo.org]

Author: neteler
Date: 2013-05-23 09:30:51 -0700 (Thu, 23 May 2013)
New Revision: 56385

Modified:
   grass/trunk/vector/v.net.path/v.net.path.html
Log:
v.net.path: explain that nodes can be inserted interactively; HTML cosmetics

Modified: grass/trunk/vector/v.net.path/v.net.path.html
===================================================================
--- grass/trunk/vector/v.net.path/v.net.path.html	2013-05-23 16:06:31 UTC (rev 56384)
+++ grass/trunk/vector/v.net.path/v.net.path.html	2013-05-23 16:30:51 UTC (rev 56385)
@@ -3,7 +3,8 @@
 <em>v.net.path</em> determines least costly, e.g. shortest or fastest 
 path(s) on a vector network.
 
-<p>Costs may be either line lengths, or attributes saved in a database 
+<p>
+Costs may be either line lengths, or attributes saved in a database 
 table. These attribute values are taken as costs of whole segments, not 
 as costs to traverse a length unit (e.g. meter) of the segment. 
 For example, if the speed limit is 100 km / h, the cost to traverse a 
@@ -12,30 +13,41 @@
 Supported are cost assignments for both arcs and nodes, 
 and also different costs for both directions of a vector line. 
 For areas, costs will be calculated along boundary lines.
-<p>The input vector needs to be prepared with <em>v.net operation=connect</em> 
+<p>
+The input vector needs to be prepared with <em>v.net operation=connect</em> 
 in order to connect points representing center nodes to the network.
 
 <p>Nodes and arcs can be closed using cost = -1. 
 <p>Least cost paths are written to the output vector map with an 
 attached attribute table.
-<p>Nodes can be piped into the program from file or from stdin. The
-syntax is as follows:
+<p>Nodes can be
+<ul>
+<li> piped into the program from file or from stdin, or
+<li> defined in the graphical user interface ("enter values interactively").
+</ul>
+
+The syntax is as follows:
 <div class="code"><pre>
 id start_point_category end_point_category
 </pre></div>
 
+(Example: 1 1 2)
+<p>
 or
 
 <div class="code"><pre>
 id start_point_x start_point_y end_point_x end_point_y
 </pre></div>
 
-<p>Points specified by category must be exactly on network nodes, and the 
+<p>
+Points specified by category must be exactly on network nodes, and the 
 input vector map needs to be prepared with <em>v.net operation=connect</em>.
-<p>When specifying coordinates, the next network node to a given coordinate 
+<p>
+When specifying coordinates, the next network node to a given coordinate 
 pair is used.
 
-<p>The attribute table will contain the following attributes:
+<p>
+The attribute table will contain the following attributes:
 
 <ul>
     <li>cat  - path unique category assigned by module</li>
@@ -47,7 +59,7 @@
         <li>     0 - OK, path found</li>
         <li>     1 - node is not reachable</li>
         <li>     2 - point of given category does not exist</li>
-    </ul></li>
+    </ul>
     <li>cost - travelling costs (on the network, not to/from network)</li>
     <li>fdist - the distance from first point to the network</li>
     <li>tdist - the distance from the network to second point</li>
@@ -62,9 +74,9 @@
 accurate results, the line length must be taken into account when 
 assigning costs as attributes. For example, to get the <b>fastest path</b>, 
 the columns 'max_speed' and 'length' are required. The correct fastest 
-path can then be found by specifying <tt>afcol=length/max_speed</tt>. If needed,
-the line length can be calculated and written to the attributes table 
-by <em>v.to.db</em>.
+path can then be found by specifying <tt>afcol=length/max_speed</tt>. If not yet
+existing, the column containing the line length ("length") has to added to the
+attributes table using <em>v.to.db</em>.
 
 <h2>EXAMPLE</h2>