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v.voronoi.1grass

NAME

v.voronoi - Creates a Voronoi diagram from an input vector map containing points or centroids.

KEYWORDS

vector

SYNOPSIS

v.voronoi
v.voronoi help
v.voronoi [-lt] input=name output=name [--overwrite] [--verbose] [--quiet]

Flags:

-l

Output tessellation as a graph (lines), not areas

-t

Do not create attribute table

--overwrite

Allow output files to overwrite existing files

--verbose

Verbose module output

--quiet

Quiet module output

Parameters:

input=name

Name of input vector map

output=name

Name for output vector map

DESCRIPTION

v.voronoi uses an existing vector points map (input) to create a Voronoi diagram (Thiessen polygons) in a new vector map (output).

The bounds of the output map are limited by the current region. (see g.region)

Voronoi diagram and Delaunay triangulation example:
       |
Delaunay Triangulation (left pane), Voronoi diagram (center pane), and both (right pane)

NOTES

Voronoi diagrams may be used for nearest-neighbor flood filling. Give the centroids attributes (start with v.db.addcol), then optionally convert to a raster map with v.to.rast.

EXAMPLE

Commands used with the Spearfish dataset to create the above figure.

  g.region n=4927250 s=4919400 w=588650 e=594850

  d.frame -c fr=one at=0,100,0,33.3333

  d.frame -c fr=two at=0,100,33.3333,66.6667

  d.frame -c fr=three at=0,100,66.6667,100


  v.delaunay -lr in=archsites out=arch_delaunay

  d.frame -s one

  d.vect arch_delaunay

  d.vect archsites color=red fcolor=red size=5 icon=basic/circle


  v.voronoi -l in=archsites out=arch_voronoi

  d.frame -s two

  d.vect arch_voronoi type=line

  d.vect archsites color=red fcolor=red size=5 icon=basic/circle


  d.frame -s three

  d.vect arch_voronoi type=line

  d.vect arch_delaunay color=blue

  d.vect archsites color=red fcolor=red size=5 icon=basic/circle

BUGS

Only attribute table of field 1 is copied.

REFERENCES

Steve J. Fortune, (1987). A Sweepline Algorithm for Voronoi Diagrams, Algorithmica 2, 153-174.

SEE ALSO

g.region, v.delaunay, v.hull

AUTHORS

James Darrell McCauley, Purdue University
GRASS 5 update, improvements: Andrea Aime, Modena, Italy
GRASS 5.7 update: Radim Blazek

Last changed: $Date: 2007-11-15 02:50:31 +0100 (gio, 15 nov 2007) $

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