NAME
v.hull - Produces a convex hull for a given vector map.
KEYWORDS
vector, geometry
SYNOPSIS
v.hull
v.hull help
v.hull [-af] input=name output=name [--overwrite] [--verbose]
[--quiet]
Flags:
-a
Use all vector points (do not limit to current region)
-f
Create a 'flat' 2D hull even if the input is 3D points
--overwrite
Allow output files to overwrite existing files
--verbose
Verbose module output
--quiet
Quiet module output
Parameters:
input=name
Name of input vector map
For vector lines reads their vertices
output=name
Name for output vector map
DESCRIPTION
v.hull computes the convex hull of a vector map and outputs the convex
hull polygon as a vector area map. The convex hull, or convex envelope,
for an object or a set of objects is the minimal convex set containing
the given objects. This module creates a vector polygon containing all
vector points or lines of the input map.
In the case of 3D input points, the hull will be a 3D hull as well,
unless the user specifies the -f flag. The 3D hull will be composed of
triangular faces.
| Fig: Convex hull polygon created with v.hull
EXAMPLE
Example of v.hull 3D output (using two random 3D point clouds, North
Carolina sample data set):
g.region rural_1m -p
r.mapcalc "zero = 0"
v.random -z output=random3d_a n=10 zmin=0 zmax=200
v.random -z output=random3d_b n=15 zmin=400 zmax=600
v.hull input=random3d_a output=random3d_a_hull
v.hull input=random3d_b output=random3d_b_hull
nviz elevation=zero vect=random3d_a_hull,random3d_b_hull
REFERENCES
(Second Edition), chapter 4.
SEE ALSO
v.delaunay
AUTHOR
Andrea Aime, Modena, Italy
Markus Neteler, ITC-irst (update to 5.7)
Benjamin Ducke, CAU Kiel (3D hull support)
Martin Landa, CTU in Prague, Czech Republic (vector lines support)
Last changed: $Date: 2013-04-14 01:55:49 -0700 (Sun, 14 Apr 2013) $
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