NAME
v.net.path - Find shortest path on vector network. Reads start/end pointsfrom standard input in format:
start_point_category end_point_category
Points must be exactly on network nodes.
SYNOPSIS
v.net.path
v.net.path help
v.net.path [-g] input=string output=string [type=string[,string,...]] [afield=integer] [nfield=integer] [afcol=string] [abcol=string] [ncol=string]
Flags:
- -g
- Use geodesic calculation for longitude-latitude locations
Parameters:
- input=string
- Name of input vector
- output=string
- Name of output vector
- type=string
- Arc type
- Options: line,boundary
- Default: line,boundary
- afield=integer
- Arc field
- Default: 1
- nfield=integer
- Node field
- Default: 2
- afcol=string
- Arc forward/both direction(s) cost column
- abcol=string
- Arc backward direction cost column
- ncol=string
- Node cost column
DESCRIPTION
v.net.path can find shortest path(s) on the vector network.
Costs may be either line lengths, or attributes saved in a database
table. These attributes values are taken as costs of whole segments. If read
from the table, arcs' costs may be different in both directions.
Shortest paths are written to output vector file and attached attribute table.
NOTE
If the columns 'afcol', 'abcol' and 'ncol' costs are not
specified, the length of network segments is measured and
zero costs are assumed for nodes.
When using attributes, the length of segments is not used. To get
more precise results, length should be taken indirectly into account
by attributes. For example, to get the fastest path the columns
'max_speed' and 'length' are required. The correct fastest path can then
be found by specifying afcol=length/max_speed (pg driver). If needed,
the line length can be calculated and written to the attributes table
by v.to.db.
SEE ALSO
d.path,
v.net,
v.net.alloc,
v.net.iso,
v.net.salesman,
v.net.steiner,
v.to.db
AUTHOR
Radim Blazek, ITC-Irst, Trento, Italy
Last changed: $Date: 2004/03/09 08:29:38 $
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