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¶

M. de Berg, M. van Kreveld, M. Overmars, O. Schwarzkopf, (2000). Computational geometry, chapter 1.1, 2-8. J. O'Rourke, (1998). Computational Geometry in C (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 10:55:49 +0200 (Sun, 14 Apr 2013) $ Full index © 2003-2014 GRASS Development Team