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

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

9       vector, geometry, grid, point pattern, hexagon
10

SYNOPSIS

12       v.mkgrid
13       v.mkgrid --help
14       v.mkgrid   [-had]   map=name   [grid=rows,columns]    [position=string]
15       [coordinates=east,north]        [box=width,height]        [angle=float]
16       [breaks=integer]   [type=string]   [--overwrite]  [--help]  [--verbose]
17       [--quiet]  [--ui]
18
19   Flags:
20       -h
21           Create hexagons (default: rectangles)
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23       -a
24           Allow asymmetric hexagons
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26       -d
27           EXPERIMENTAL: Add diagonals to rectangular lines
28           Applies only to lines for rectangles
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30       --overwrite
31           Allow output files to overwrite existing files
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33       --help
34           Print usage summary
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36       --verbose
37           Verbose module output
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39       --quiet
40           Quiet module output
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42       --ui
43           Force launching GUI dialog
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45   Parameters:
46       map=name [required]
47           Name for output vector map
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49       grid=rows,columns
50           Number of rows and columns in grid
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52       position=string
53           Where to place the grid
54           Options: region, coor
55           Default: region
56           region: current region
57           coor: use ’coor’ and ’box’ options
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59       coordinates=east,north
60           Lower left easting and northing coordinates of map
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62       box=width,height
63           Width and height of boxes in grid
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65       angle=float
66           Angle of rotation (in degrees counter-clockwise)
67           Default: 0
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69       breaks=integer
70           Number of vertex points per grid cell
71           Options: 0-60
72           Default: 0
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74       type=string
75           Output feature type
76           Options: point, line, area
77           Default: area
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DESCRIPTION

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

84       Grid  points  created  with the type=point option will be placed at the
85       center of each grid cell, like centroids with the default type=area op‐
86       tion.
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88       Grid  lines  created with the type=line option will be identical to the
89       edges of each grid cell, like boundaries with the default type=area op‐
90       tion.
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92       The  resultant  grid  can  be  rotated around the origin (center of the
93       grid) with the angle option.
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95       Optionally hexagons can be created with the -h flag.  Hexagons  are  by
96       default symmetric. Asymmetric hexagons can be allowed with the -a flag.
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98       This module is NOT to be used to generate a vector map of USGS quadran‐
99       gles, because USGS quads are not exact rectangles.
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EXAMPLES

102   Creating a global grid in a latitude-longitude
103       To be run in a latitude-longitude location (WGS84)
104       # set the region:
105       g.region n=90 s=-90 w=-180 e=180 res=10 -p
106       projection: 3 (Latitude-Longitude)
107       zone:       0
108       datum:      wgs84
109       ellipsoid:  wgs84
110       north:      90N
111       south:      90S
112       west:       180W
113       east:       180E
114       nsres:      10
115       ewres:      10
116       rows:       18
117       cols:       36
118       cells:      648
119       # create 10 degree size grid:
120       v.mkgrid map=grid_10deg
121       # create 20 degree size grid:
122       v.mkgrid map=grid_20deg box=20,20
123
124   Creating a grid in a metric projection
125       Creating a 4x3 grid, cells 20km a  side,  with  lower  left  corner  at
126       2716500,6447000:
127       v.mkgrid map=coro_grid grid=4,3 position=coor coordinates=2716500,6447000 box=20000,20000
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129   Creating a positioned grid in a latitude-longitude
130       Creating  a 10x12 lat/lon grid, cells 2 arc-min a side, with lower left
131       corner at 167deg 52min east, 47deg 6min south. For use with  e.g.  QGIS
132       you  can  then pull this grid into a projected location with v.proj be‐
133       fore exporting as a Shapefile with  v.out.ogr  (within  GRASS  GIS  you
134       could  just  use d.grid -w from the projected location for the same ef‐
135       fect):
136       v.mkgrid map=p2min_grid grid=10,12 position=coor coordinates=167:52E,47:06S box=0:02,0:02
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138   Creating a simple point pattern
139       North Carolina sample dataset example, creating a 1km spaced point grid
140       based on the current region extent defined by the "elevation" map:
141       g.region raster=elevation res=1000 -pa
142       v.mkgrid type=point map=pointpattern
143
144   Creating a regular point pattern
145       North  Carolina sample dataset example, creating a regular spaced point
146       grid based on the current region extent defined by the "elevation" map,
147       using a two-step approach:
148       # create first set of points, covering extent of "elevation" raster map
149       g.region raster=elevation res=1000 -pa
150       v.mkgrid type=point map=pointpattern1
151       # shift grid by half point distance (map units)
152       g.region n=n+500 w=w+500 e=e+500 s=s+500 -p
153       # create second set of points
154       v.mkgrid type=point map=pointpattern2
155       # merge into final point pattern
156       v.patch input=pointpattern1,pointpattern2 output=pointpattern3
157       Different point patterns for sampling design
158
159   Creating hexagons in a metric projection
160       North  Carolina sample dataset example, creating regular hexagons based
161       on the current region extent defined by the "elevation" map and  raster
162       resolution for the hexagon size:
163       g.region raster=elevation res=5000 -pa
164       v.mkgrid map=hexagons -h
165       d.grid 5000
166       Hexagon map
167
168   Using hexagons for point density
169       To  compute  point  density  in  a  hexagonal  grid  for the vector map
170       points_of_interest in the basic North Carolina sample dataset, the vec‐
171       tor  map itself is used to set extent of the computational region.  The
172       resolution is based on the desired size of hexagons.
173       g.region vector=points_of_interest res=2000 -pa
174       The hexagonal grid is created as a vector map based on  the  previously
175       selected extent and size of the grid.
176       v.mkgrid map=hexagons -h
177       The  following  counts  the  number  of  points  per  hexagon using the
178       v.vect.stats module.
179       v.vect.stats points=points_of_interest areas=hexagons count_column=count
180       User should note that some of the points may be outside the grid  since
181       the  hexagons  cannot cover all the area around the edges (the computa‐
182       tional region extent needs to be enlarged if all points should be  con‐
183       sidered).   The last command sets the vector map color table to viridis
184       based on the count column.
185       v.colors map=hexagons use=attr column=count color=viridis
186       Point density in a hexagonal grid
187

SEE ALSO

189        d.grid, v.in.region, v.patch, v.vect.stats
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AUTHORS

192       Michael Higgins, U.S.Army Construction Engineering Research Laboratory
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194       Update for new vectors Radim Blazek 10/2004
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SOURCE CODE

197       Available at: v.mkgrid source code (history)
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199       Accessed: Mon Jun 20 16:47:05 2022
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201       Main index | Vector index | Topics index | Keywords index  |  Graphical
202       index | Full index
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204       © 2003-2022 GRASS Development Team, GRASS GIS 8.2.0 Reference Manual
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208GRASS 8.2.0                                                        v.mkgrid(1)
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