break
breaks lines and sets a node at each intersection
rmdupl
removes duplicate lines (pay attention to categories!)
snap
snaps vertex to a line and create new vertex at that line
rmdac
removes duplicate area centroids ('type' option ignored)
You do not have to run v.build afterwards.
What is a bridge?
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). v.clean can be used to optionally change the line type to fulfill the topology rules or to remove the bridge from the map:
+-------------+ +-------------+ +-------------+
| P| P: polygon | P| | P|
| +---+ | I: island | +---+ | | +---+ |
| | I | | B: bridge | | I | | | | I | |
| | | | : line | | | | | | | |
| +-+-+ | | +---+ | | +-.-+ |
| | | | | | . |
| | B | | | | . L |
| | | | | | . |
+------+------+ +-------------+ +-------------+
v.clean input=testmap output=cleanmap tool=svtlx breakthresh=1
The import of areas with v.in.ogr requires a subsequent run of v.clean to update the map to a topologically valid structure (removal of duplicate collinear lines etc). The tools used for that are 'rmdupl' and 'bpol':
v.clean input=areamap output=areamap_clean tool=rmdupl,bpol
Last changed: $Date: 2004/03/10 13:26:14 $