DESCRIPTION

v.clean allows the user to automatically change (repair) vector files. The user does not have to run v.build afterwards.

NOTES

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    |
    |      |      |             |             |   |      .      |
    +------+------+             +-------------+   +-------------+

EXAMPLES

Snap lines to vertex in threshold

v.clean input=testmap output=cleanmap tool=snap thresh=1

Cleaning OGR imported data (Simple Feature data)

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

Extracting intersection points of vector lines

v.clean input=lines1 output=lines2 err=points tool=break
Intersection points are written to 'points' map.

AUTHOR

David Gerdes, U.S. Army Construction Engineering Research Laboratory
Radim Blazek, ITC-Irst, Trento, Italy

Last changed: $Date$