[GRASS-SVN] r53393 - grass/trunk/vector/v.net
svn_grass at osgeo.org
svn_grass at osgeo.org
Sun Oct 14 23:46:27 PDT 2012
Author: neteler
Date: 2012-10-14 23:46:27 -0700 (Sun, 14 Oct 2012)
New Revision: 53393
Modified:
grass/trunk/vector/v.net/v.net.html
Log:
HTML cleanup
Modified: grass/trunk/vector/v.net/v.net.html
===================================================================
--- grass/trunk/vector/v.net/v.net.html 2012-10-15 05:58:40 UTC (rev 53392)
+++ grass/trunk/vector/v.net/v.net.html 2012-10-15 06:46:27 UTC (rev 53393)
@@ -1,34 +1,36 @@
<h2>DESCRIPTION</h2>
-<h3><em>v.net</em> is used for network preparation and maintenance. Its main
+<em>v.net</em> is used for network preparation and maintenance. Its main
use is to create a vector network from vector lines (<em>arcs</em>) and points
(<em>nodes</em>) by creating nodes from intersections in a map of vector
lines (<em>node</em> operator), by connecting a vector lines map with a points map
(<em>connect</em> operator), and by creating new lines between pairs of vector points
-(<em>arcs</em> operator).</h3>
+(<em>arcs</em> operator).
-<p>A GIS network consists of topologically correct lines (arcs). That is,
+<p>
+A GIS network consists of topologically correct lines (arcs). That is,
the lines must be connected by shared vertices where real connections exist.
In GRASS you also can add nodes to the network. These are specially
designated vertices used for analyzing network properties or computing
cost/distance measures. That is, not all vertices are treated as nodes by
-default. Only <em><a href="v.net.path.html">v.net.path</a></em> can use a network without nodes, they are required
-for all the other network modules. In GRASS, network arcs are stored in one
-data layer (normally layer 1) and nodes are stored in a different data layer
-(normally layer 2).
+default. Only <em><a href="v.net.path.html">v.net.path</a></em> can use a
+network without nodes, they are required for all the other network modules.
+In GRASS, network arcs are stored in one data layer (normally layer 1) and
+nodes are stored in a different data layer (normally layer 2).
-<p><em>v.net</em> offers two ways to add nodes to a network of arcs and one
+<p>
+<em>v.net</em> offers two ways to add nodes to a network of arcs and one
method to add arcs to a set of nodes:
<ol>
-<li><p>Use the <em>connect</em> operation to create nodes from a vector points
+<li>Use the <em>connect</em> operation to create nodes from a vector points
file and add these nodes to an existing vector network of arcs (i.e.,
lines/boundaries). This is useful when the goal is to analyze a set of places
(points) in relation to a network--for example travel costs between places.
Only points within the <em>thresh</em> (threshold) distance to a line/boundary
will be connected as network nodes.</li>
-<li><p>Create nodes and arcs from a vector line/boundary file using the <em>node</em>
+<li>Create nodes and arcs from a vector line/boundary file using the <em>node</em>
operation. This is useful if you are mostly interested in the
network itself and thus you can use intersections of the network as start and
end points. Nodes will be created at all intersections of two or more lines.
@@ -42,34 +44,40 @@
software, making it possible to create georeferenced social networks.</li>
</ol>
-<p>While the arcs created with v.net will retain any attribute information
+<p>
+While the arcs created with v.net will retain any attribute information
associated with the input vector line/boundary file in data layer 1, nodes
created and stored in data layer 2 will not have any associated attribute
information.
-<p>For nodes created using the <em>connect</em> and <em>arcs</em> operations (methods 1
+<p>
+For nodes created using the <em>connect</em> and <em>arcs</em> operations (methods 1
and 3 above), the nodes can be reconnected to the attribute table of the
input vector points file using the attribute table manager ("manage layers"
tab) or by running (<em><a href="v.db.connect.html">v.db.connect</a></em>).
-<p>For nodes created using the <em>nodes</em> operation
+<p>
+For nodes created using the <em>nodes</em> operation
(method 2 above), it is possible to create an attribute table for the
new nodes in layer 2 using the attribute table manager and connect it to
layer 2 ("manage layers" tab) or to create a table with v.db.addtable,
-connect it to layer 2 with (<em><a href="v.db.connect.html">v.db.connect</a></em>), and update the new table with
-cat values with (<em><a href="v.to.db.html">v.to.db</a></em>).
+connect it to layer 2 with (<em><a href="v.db.connect.html">v.db.connect</a></em>),
+and update the new table with cat values with (<em><a href="v.to.db.html">v.to.db</a></em>).
-<p>Once a vector network has been created, it can be analyzed in a number
+<p>
+Once a vector network has been created, it can be analyzed in a number
of powerful ways using the suite of <em>v.net</em>.* modules. The shortest route
between two nodes, following arcs, can be computed (<em><a href="v.net.path.html">v.net.path</a></em>), as can the
shortest route that will pass through a set of nodes and return to the
-starting node (<em><a href="v.net.salesman.html">v.net.salesman</a></em>). Least cost routes through the network can be
-calculated on the basis of distance only or on the basis of distance weighted
-by an attribute associated with each arc (for example, travel speed along a
-network segment). A network can be divided into concentric zones of equal travel cost around
-one or more nodes (<em><a href="v.net.iso.html">v.net.iso</a></em>) or subdivided so that each node is surrounded
-by a zone in which all arcs can be reached with the same travel costs as all
-arcs surrounding each other node (<em><a href="v.net.alloc.html">v.net.alloc</a></em>).</p>
+starting node (<em><a href="v.net.salesman.html">v.net.salesman</a></em>).
+Least cost routes through the network can be calculated on the basis of
+distance only or on the basis of distance weighted by an attribute
+associated with each arc (for example, travel speed along a network segment).
+A network can be divided into concentric zones of equal travel cost around
+one or more nodes (<em><a href="v.net.iso.html">v.net.iso</a></em>) or
+subdivided so that each node is surrounded by a zone in which all arcs
+can be reached with the same travel costs as all arcs surrounding each
+other node (<em><a href="v.net.alloc.html">v.net.alloc</a></em>).
In addition to the modules listed above, the GRASS vector networking suite
includes numerous other modules for analysis of network costs and
@@ -96,11 +104,11 @@
digitizer</a></em> or <em><a href="v.edit.html">v.edit</a></em> can be
used.
See also the <a href="lrs.html">Linear Referencing System</a> available in
-GRASS.
+GRASS GIS.
<h3>EXAMPLES</h3>
-<a href="http://www.grassbook.org/data_menu3rd.php">NC dataset</a> based examples.
+The examples are <a href="http://www.grassbook.org/data_menu3rd.php">North Carolina dataset</a> based.
<p>Create nodes globally for all line ends and intersections:
@@ -131,8 +139,8 @@
<h2>SEE ALSO</h2>
<em>
- <a href="wxGUI.Vector_Digitizer.html">wxGUI vector digitizer</a>,
- <a href="v.edit.html">v.edit</a><br>
+<a href="wxGUI.Vector_Digitizer.html">wxGUI vector digitizer</a>,
+<a href="v.edit.html">v.edit</a>
</em>
<h2>AUTHORS</h2>
@@ -142,4 +150,5 @@
Martin Landa, FBK-irst (formerly ITC-irst), Trento, Italy and CTU in
Prague, Czech Republic (operation 'connect' and 'arcs')
-<p><i>Last changed: $Date$</i>
+<p>
+<i>Last changed: $Date$</i>
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