Quick Navigator

Search Site

Unix VPS
A - Starter
B - Basic
C - Preferred
D - Commercial
MPS - Dedicated
Previous VPSs
* Sign Up! *

Contact Us
Online Help
Domain Status
Man Pages

Virtual Servers

Topology Map

Server Agreement
Year 2038

USA Flag



Man Pages
v.hull(1) Grass User's Manual v.hull(1)

v.hull - Produces a 2D/3D convex hull for a given vector map.

vector, geometry, 3D

v.hull --help
v.hull [-rf] input=name [layer=string] output=name [cats=range] [where=sql_query] [-- overwrite] [--help] [--verbose] [-- quiet] [--ui]

Limit to current region
Create a ’flat’ 2D hull even if the input is 3D points
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog

input=name [required]
Name of input vector map
Or data source for direct OGR access
Layer number or name (’-1’ for all layers)
A single vector map can be connected to multiple database tables. This number determines which table to use. When used with direct OGR access this is the layer name.
Default: -1
output=name [required]
Name for output vector map
Category values
Example: 1,3,7-9,13
WHERE conditions of SQL statement without ’where’ keyword
Example: income < 1000 and population >= 10000

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

In order to use the where option the layer option must be set to a positive number (the default is ’-1’ for ’all layers’), otherwise all points from all layers will be used and the cats and where options will be ignored.

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
d.mon wx0
d.vect random3d_a_hull
d.vect random3d_a color=red
d.vect random3d_b_hull
d.vect random3d_b color=red
# 3D view in wxGUI (g.gui)
Fig: Convex hull in 3D from 3D points created with v.hull

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.


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: 2018-02-22 20:16:03 +0100 (Thu, 22 Feb 2018) $

Available at: v.hull source code (history)
Main index | Vector index | Topics index | Keywords index | Graphical index | Full index
© 2003-2018 GRASS Development Team, GRASS GIS 7.4.3 Reference Manual
GRASS 7.4.3

Search for    or go to Top of page |  Section 1 |  Main Index

Powered by GSP Visit the GSP FreeBSD Man Page Interface.
Output converted with ManDoc.