1r.buffer(1)                   Grass User's Manual                  r.buffer(1)
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NAME

6       r.buffer  - Creates a raster map showing buffer zones surrounding cells
7       that contain non-NULL category values.
8

KEYWORDS

10       raster, buffer
11

SYNOPSIS

13       r.buffer
14       r.buffer --help
15       r.buffer  [-z]   input=name   output=name   distances=float[,float,...]
16       [units=string]     [--overwrite]    [--help]    [--verbose]   [--quiet]
17       [--ui]
18
19   Flags:
20       -z
21           Ignore zero (0) data cells instead of NULL cells
22
23       --overwrite
24           Allow output files to overwrite existing files
25
26       --help
27           Print usage summary
28
29       --verbose
30           Verbose module output
31
32       --quiet
33           Quiet module output
34
35       --ui
36           Force launching GUI dialog
37
38   Parameters:
39       input=name [required]
40           Name of input raster map
41
42       output=name [required]
43           Name for output raster map
44
45       distances=float[,float,...] [required]
46           Distance zone(s)
47
48       units=string
49           Units of distance
50           Options: meters, kilometers, feet, miles, nautmiles
51           Default: meters
52

DESCRIPTION

54       r.buffer creates a new raster map showing buffer (a.k.a. "distance"  or
55       "proximity") zones around all cells that contain non-NULL category val‐
56       ues in an existing raster map. The distances of buffer zones from cells
57       with  non-zero  category  values  are  user-chosen and must be positive
58       value(s).  Suppose, for example, that you want to  place  buffer  zones
59       around  roads.  This program could create the raster map shown below on
60       the right based on road information contained in the raster  map  shown
61       on the left.
62             000000000000000000000000 222233333333333333444444
63             111000000000000000000000 111222222222223333333333
64             000111111111100000000000 222111111111122223333333
65             000000001000011100000000 332222221222211122222222
66             000000001000000011111111 333333321233222211111111
67             000000001000000000000000 433333321233333222222222
68             000000001000000000000000 444443321233333333333333
69             000000001000000000000000 444443321233443333333333
70             000000001000000000000000 444443321233444444444444
71             Category 0: No roads
72             Category 1: Road location
73             Category 2: Buffer Zone 1 around roads
74             Category 3: Buffer Zone 2 around roads
75             Category 4: Buffer Zone 3 around roads
76

NOTES

78       The user has the option of identifying up to 250 continuous zones.  The
79       zones are identified by specifying the upper limit of each desired zone
80       (r.buffer  assumes that 0 is the starting point).  "Continuous" is used
81       in the sense that each category zone’s  lower  value  is  the  previous
82       zone’s  upper value. The first buffer zone always has distance 0 as its
83       lower bound. Buffer distances can be specified using one of five  units
84       with the units parameter.
85
86       Distances  from cells containing the user-specified category values are
87       calculated using the "fromcell" method. This method locates  each  cell
88       that  contains  a  category value from which distances are to be calcu‐
89       lated, and draws the requested distance rings around them. This  method
90       works very fast when there are few cells containing the category values
91       of interest, but works slowly when there are numerous cells  containing
92       the category values of interest spread throughout the area.
93
94       r.buffer measures distances from center of cell to center of cell using
95       Euclidean distance measure for planimetric  locations  (like  UTM)  and
96       using  ellipsoidal  geodesic  distance  measure  for latitude/longitude
97       locations.
98
99       r.buffer calculates distance zones from all cells having non-NULL cate‐
100       gory values in the input map. If the user wishes to calculate distances
101       from only selected input map category values, the user should run  (for
102       example)  r.reclass  prior  to r.buffer, to reclass all categories from
103       which distance zones are not desired to  be  calculated  into  category
104       NULL.
105
106       The -z flag can be used to ignore raster values of zero instead of NULL
107       values in the input raster map.
108
109       When working with massive raster regions consider  the  r.buffer.lowmem
110       module  if  RAM  use becomes a problem. The lowmem version can be > 40x
111       slower, but will work with minimal  memory  requirements.  The  classic
112       r.buffer should be able to deal with raster maps of 32000x32000 size on
113       a system with 1 GB RAM, and rasters of 90000x90000 on a system  with  8
114       GB RAM without going into swap.
115

EXAMPLE

117       In  the  following  example (North Carolina sample dataset), the buffer
118       zones would be (in the default map units of meters):   0-100,  101-200,
119       201-300, 301-400 and 401-500.
120       g.region raster=roadsmajor -p
121       r.buffer input=roadsmajor output=roadsmajor_buf distances=100,200,300,400,500
122       Result:
123       r.category input=roads.buf
124             1       distances calculated from these locations
125             2       0-100 meters
126             3       100-200 meters
127             4       200-300 meters
128             5       300-400 meters
129             6       400-500 meters
130       Distances to road
131

SEE ALSO

133        r.buffer.lowmem, r.grow, v.buffer
134
135        g.region, r.cost, r.distance, r.grow.distance, r.mapcalc, r.reclass
136

AUTHORS

138       Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
139       James  Westervelt,  U.S. Army Construction Engineering Research Labora‐
140       tory
141

SOURCE CODE

143       Available at: r.buffer source code (history)
144
145       Main index | Raster index | Topics index | Keywords index  |  Graphical
146       index | Full index
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148       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual
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152GRASS 7.8.2                                                        r.buffer(1)
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