v.net.curvedarcs - GRASS GIS manual

NAME

v.net.curvedarcs - Draws curved arcs between points (e.g. flows)

KEYWORDS

SYNOPSIS

v.net.curvedarcs

v.net.curvedarcs --help

v.net.curvedarcs [-s] input=name [layer=string] flow_input_file=name [separator=character] output=name minimum_offset=float maximum_offset=float [vertices=integer] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

-s: Draw also short line for flow from and to same node
--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]: Point map containing origins and destinations; Or data source for direct OGR access
layer=string: Layer number where to find point categories; Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.; Default: 1
flow_input_file=name [required]: File containing origins, destinations and flow volumes; Name of input file
separator=character: Separator used in input text file; Special characters: pipe, comma, space, tab, newline; Default: pipe
output=name [required]: Output map with curved lines; Name for output vector map
minimum_offset=float [required]: minimum offset at furthest point from straight line
maximum_offset=float [required]: maximum offset at furthest point from straight line
vertices=integer: number of vertices used to draw curved lines; Default: 30

DESCRIPTION
NOTES
EXAMPLE
SEE ALSO
AUTHORS

DESCRIPTION

v.net.curvedarcs is a frontend to v.net and v.segment that creates curved arcs between given start and end points. The user provides a point vector map and a text file (see Notes section) with start and end point categories as well as a flow volume for this link which will be transferred to the attribute table of the curved arcs.

The user can determine the nature of the curve with the minimum_offset and maximum_offset parameters. The longest curve's maximum offset from a straight line is equal to the value of maximum_offset in map units. The other curves maximum offset from a straight line is calulated as length(x)/max_length * max_offset. In other words, shorter lines are less curved than longer lines. However, any line's maximum offset is always at least minimum_offset from the straight line.

NOTES

EXAMPLE

TODO

v.extract census_wake2000 cat=1,52,70,99,101 type=centroid out=tmp
v.type tmp from=centroid to=point out=points
echo >> flows.txt << EOF
> from,to,volume
> 52,1,100
> 1,52,50
> 70,1,50
> 1,70,50
> 99,1,66
> 1,99,100
> 101,1,25
> 1,101,75
> EOF
v.net.curvedarcs in=points flow=flows.txt sep=comma out=flows minoff=0 maxoff=2000
d.vect map=flows display=shape,dir width_column=volume width_scale=0.05 size=10
d.vect map=points display=shape,cat fill_color=red icon=basic/circle label_bcolor=black label_size=12 yref=bottom

The curved arcs with minimum offset = 150 and maximum offset = 2000

Using different amount of curvature:

v.net.curvedarcs in=points flow=flows.txt sep=comma out=flows minoff=150 maxoff=5000 --o
d.vect map=flows display=shape,dir width_column=volume width_scale=0.05 size=10
d.vect map=points display=shape,cat fill_color=red icon=basic/circle label_bcolor=black label_size=12 yref=bottom