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v.mkgrid(1)		    GRASS GIS User's Manual		   v.mkgrid(1)

NAME
       v.mkgrid	 - Creates a vector map	of a user-defined grid.

KEYWORDS
       vector, geometry, grid, point pattern, hexagon

SYNOPSIS
       v.mkgrid
       v.mkgrid	--help
       v.mkgrid	  [-had]   map=name   [grid=rows,columns]    [position=string]
       [coordinates=east,north]	       [box=width,height]	 [angle=float]
       [breaks=integer]	  [type=string]	  [--overwrite]	 [--help]  [--verbose]
       [--quiet]  [--ui]

   Flags:
       -h
	   Create hexagons (default: rectangles)

       -a
	   Allow asymmetric hexagons

       -d
	   EXPERIMENTAL: Add diagonals to rectangular lines
	   Applies only	to lines for rectangles

       --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:
       map=nameA [required]
	   Name	for output vector map

       grid=rows,columns
	   Number of rows and columns in grid

       position=string
	   Where to place the grid
	   Options: region, coor
	   Default: region
	   region: current region
	   coor: use 'coor' and	'box' options

       coordinates=east,north
	   Lower left easting and northing coordinates of map

       box=width,height
	   Width and height of boxes in	grid

       angle=float
	   Angle of rotation (in degrees counter-clockwise)
	   Default: 0

       breaks=integer
	   Number of vertex points per grid cell
	   Options: 0-60
	   Default: 0

       type=string
	   Output feature type
	   Options: point, line, area
	   Default: area

DESCRIPTION
       v.mkgrid	creates	a vector map representation of	a  regular  coordinate
       grid. Point, line, and area vector grids	can be created.

NOTES
       Grid  points  created  with the type=point option will be placed	at the
       center of each grid cell, like centroids	with the default type=area op-
       tion.

       Grid  lines  created with the type=line option will be identical	to the
       edges of	each grid cell,	like boundaries	with the default type=area op-
       tion.

       The  resultant  grid  can  be  rotated around the origin	(center	of the
       grid) with the angle option.

       Optionally hexagons can be created with the -h flag.  Hexagons  are  by
       default symmetric. Asymmetric hexagons can be allowed with the -a flag.

       This module is NOT to be	used to	generate a vector map of USGS quadran-
       gles, because USGS quads	are not	exact rectangles.

EXAMPLES
   Creating a global grid in a latitude-longitude
       To be run in a latitude-longitude location (WGS84)
       # set the region:
       g.region	n=90 s=-90 w=-180 e=180	res=10 -p
       projection: 3 (Latitude-Longitude)
       zone:	   0
       datum:	   wgs84
       ellipsoid:  wgs84
       north:	   90N
       south:	   90S
       west:	   180W
       east:	   180E
       nsres:	   10
       ewres:	   10
       rows:	   18
       cols:	   36
       cells:	   648
       # create	10 degree size grid:
       v.mkgrid	map=grid_10deg
       # create	20 degree size grid:
       v.mkgrid	map=grid_20deg box=20,20

   Creating a grid in a	metric projection
       Creating	a 4x3 grid, cells 20km a  side,	 with  lower  left  corner  at
       2716500,6447000:
       v.mkgrid	map=coro_grid grid=4,3 position=coor coordinates=2716500,6447000 box=20000,20000

   Creating a positioned grid in a latitude-longitude
       Creating	 a 10x12 lat/lon grid, cells 2 arc-min a side, with lower left
       corner at 167deg	52min east, 47deg 6min south. For use with  e.g.  QGIS
       you  can	 then pull this	grid into a projected location with v.proj be-
       fore exporting as a Shapefile with  v.out.ogr  (within  GRASS  GIS  you
       could  just  use	d.grid -w from the projected location for the same ef-
       fect):
       v.mkgrid	map=p2min_grid grid=10,12 position=coor	coordinates=167:52E,47:06S box=0:02,0:02

   Creating a simple point pattern
       North Carolina sample dataset example, creating a 1km spaced point grid
       based on	the current region extent defined by the "elevation" map:
       g.region	raster=elevation res=1000 -pa
       v.mkgrid	type=point map=pointpattern

   Creating a regular point pattern
       North  Carolina sample dataset example, creating	a regular spaced point
       grid based on the current region	extent defined by the "elevation" map,
       using a two-step	approach:
       # create	first set of points, covering extent of	"elevation" raster map
       g.region	raster=elevation res=1000 -pa
       v.mkgrid	type=point map=pointpattern1
       # shift grid by half point distance (map	units)
       g.region	n=n+500	w=w+500	e=e+500	s=s+500	-p
       # create	second set of points
       v.mkgrid	type=point map=pointpattern2
       # merge into final point	pattern
       v.patch input=pointpattern1,pointpattern2 output=pointpattern3
       Different point patterns	for sampling design

   Creating hexagons in	a metric projection
       North  Carolina sample dataset example, creating	regular	hexagons based
       on the current region extent defined by the "elevation" map and	raster
       resolution for the hexagon size:
       g.region	raster=elevation res=5000 -pa
       v.mkgrid	map=hexagons -h
       d.grid 5000
       Hexagon map

   Using hexagons for point density
       To  compute  point  density  in	a  hexagonal  grid  for	the vector map
       points_of_interest in the basic North Carolina sample dataset, the vec-
       tor  map	itself is used to set extent of	the computational region.  The
       resolution is based on the desired size of hexagons.
       g.region	vector=points_of_interest res=2000 -pa
       The hexagonal grid is created as	a vector map based on  the  previously
       selected	extent and size	of the grid.
       v.mkgrid	map=hexagons -h
       The  following  counts  the  number  of	points	per  hexagon using the
       v.vect.stats module.
       v.vect.stats points=points_of_interest areas=hexagons count_column=count
       User should note	that some of the points	may be outside the grid	 since
       the  hexagons  cannot cover all the area	around the edges (the computa-
       tional region extent needs to be	enlarged if all	points should be  con-
       sidered).   The last command sets the vector map	color table to viridis
       based on	the count column.
       v.colors	map=hexagons use=attr column=count color=viridis
       Point density in	a hexagonal grid

SEE ALSO
	d.grid,	v.in.region, v.patch, v.vect.stats

AUTHORS
       Michael Higgins,	U.S.Army Construction Engineering Research Laboratory

       Update for new vectors Radim Blazek 10/2004

SOURCE CODE
       Available at: v.mkgrid source code (history)

       Main index | Vector index | Topics index	| Keywords index  |  Graphical
       index | Full index

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.3 Reference	Manual

GRASS 7.8.3							   v.mkgrid(1)

NAME | KEYWORDS | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLES | SEE ALSO | AUTHORS | SOURCE CODE

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