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

       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)

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 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

       vector, geometry, 3D

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

       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.

           •   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.

v.delaunay

       Available at: v.hull source code (history)

       Accessed: Friday Apr 04 01:20:17 2025

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       © 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual

GRASS 8.4.1                                                                                       v.hull(1grass)

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

   Flags:-r
           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

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:input=name[required]
           Name of input vector map
           Or data source for direct OGR access

       layer=string
           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: -1output=name[required]
           Name for output vector map

       cats=range
           Category values
           Example: 1,3,7-9,13

       where=sql_query
           WHERE conditions of SQL statement without ’where’ keyword
           Example: income < 1000 and population >= 10000