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<h2>DESCRIPTION</h2>
<em>v.clean</em> allows the user to automatically change (repair) vector files.
The user does <em>not</em> have to run <em><a HREF="v.build.html">v.build</a></em> afterwards.
<h2>NOTES</h2>
<h3>What is a bridge?</h3>
A bridge is an area type connection of an island (polygon in a polygon) to the outer
polygon. This is topologically incorrect (but OGC Simple Features allow it). <em>v.clean</em>
can be used to optionally change the line type to fulfill the topology rules or to
remove the bridge from the map:
<pre>
+-------------+ +-------------+ +-------------+
| P| P: polygon | P| | P|
| +---+ | I: island | +---+ | | +---+ |
| | I | | B: bridge | | I | | | | I | |
| | | | : line | | | | | | | |
| +-+-+ | | +---+ | | +-.-+ |
| | | | | | . |
| | B | | | | . L |
| | | | | | . |
+------+------+ +-------------+ +-------------+
</pre>
<h2>EXAMPLES</h2>
<h3>Snap lines to vertex in threshold</h3>
<b>v.clean input=</b><em>testmap</em> <b>output=</b><em>cleanmap</em> <b>tool=</b><em>snap</em> <b>thresh=</b><em>1</em>
<p>
<h3>Cleaning OGR imported data (Simple Feature data)</h3>
The import of areas with <a HREF="v.in.ogr.html">v.in.ogr</a> requires a subsequent run of
<a HREF="v.clean.html">v.clean</a> to update the map to a topologically
valid structure (removal of duplicate collinear lines etc). The tools
used for that are 'rmdupl' and 'bpol':
<p>
<b>v.clean input=</b><em>areamap</em> <b>output=</b><em>areamap_clean</em> <b>tool=</b><em>rmdupl,bpol</em> <br>
<h3>Extracting intersection points of vector lines</h3>
<b>v.clean input=</b><em>lines1</em> <b>output=</b><em>lines2</em> <b>err=</b><em>points</em> <b>tool=</b><em>break</em> <br>
Intersection points are written to 'points' map.
<h2>AUTHOR</h2>
David Gerdes, U.S. Army Construction Engineering
Research Laboratory
<br>
Radim Blazek, ITC-Irst, Trento, Italy
<p><i>Last changed: $Date: 2004/08/07 15:56:22 $</i>
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