GRASS GIS manual: v.lfp

NAME

v.lfp - Converts a longest flow path raster map created by r.lfp to a vector map.

KEYWORDS

SYNOPSIS

v.lfp

v.lfp --help

v.lfp input=name output=name [coordinates=east,north] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

--overwrite: Allow output files to overwrite existing files
--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters:

input=name [required]: Name of input longest flow path raster map
output=name [required]: Name for output longest flow path vector map
coordinates=east,north: Coordinates of outlet point; Optionally required to ensure the downstream direction of the output line

DESCRIPTION
NOTES
EXAMPLE
SEE ALSO
AUTHOR

DESCRIPTION

v.lfp converts a longest flow path raster map created by r.lfp to a vector map.

v.lfp creates a longest flow path vector map by processing an output raster map from r.lfp. Since a longest flow path raster map can have cell clusters, simply converting the raster map to a vector map using r.to.vect can result in closed rectangular shapes in the output vector map, which represent multiple but equivalent longest flow paths. This module first converts the input raster map to a vector map, removes dangles, and merge the remaining lines. The module repeats this process until there remains only one line feature, which is the final longest flow path.

EXAMPLE

# Creates a longest flow path raster map.
r.watershed elevation=elev drainage=drain
r.water.outlet input=drain output=basin coordinates=-888857.11,1117788.38
r.lfp input=drain output=lfp coordinates=-888857.11,1117788.38

# The end point of lfp can be the headwater of the longest flow path.
v.lfp input=lfp output=lfp

# Make sure the end point of lfp2 is the outlet point.
v.lfp input=lfp output=lfp2 coordinates=-888857.11,1117788.38

AUTHOR

Huidae Cho

Last changed: $Date: 2016-08-15 23:01:53 +0200 (Mon, 15 Aug 2016) $

SOURCE CODE

Available at: v.lfp source code (history)