1r.buffer(1) Grass User's Manual r.buffer(1)
2
6 r.buffer - Creates a raster map showing buffer zones surrounding cells
7 that contain non-NULL category values.
8
10 raster, buffer
11
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 Flags:
20 -z
21 Ignore zero (0) data cells instead of NULL cells
22 --overwrite
24 Allow output files to overwrite existing files
25 --help
27 Print usage summary
28 --verbose
30 Verbose module output
31 --quiet
33 Quiet module output
34 --ui
36 Force launching GUI dialog
37 Parameters:
39 input=name [required]
40 Name of input raster map
41 output=name [required]
43 Name for output raster map
44 distances=float[,float,...] [required]
46 Distance zone(s)
47 units=string
49 Units of distance
50 Options: meters, kilometers, feet, miles, nautmiles
51 Default: meters
52
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
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 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 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 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 The -z flag can be used to ignore raster values of zero instead of NULL
107 values in the input raster map.
108 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
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
133 r.buffer.lowmem, r.grow, v.buffer
134 g.region, r.cost, r.distance, r.grow.distance, r.mapcalc, r.reclass
136
138 Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
139 James Westervelt, U.S. Army Construction Engineering Research Labora‐
140 tory
141 Last changed: $Date: 2016-01-21 12:10:11 +0100 (Thu, 21 Jan 2016) $
143
145 Available at: r.buffer source code (history)
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149 © 2003-2019 GRASS Development Team, GRASS GIS 7.6.0 Reference Manual
151GRASS 7.6.0 r.buffer(1)