1r.buffer(1) Grass User's Manual r.buffer(1)
2
6 r.buffer - Creates a raster map layer showing buffer zones surrounding
7 cells that contain non-NULL category values.
8
10 raster, buffer
11
13 r.buffer
14 r.buffer help
15 r.buffer [-zq] input=name output=name distances=float[,float,...]
16 [units=string] [--overwrite] [--verbose] [--quiet]
17 Flags:
19 -z
20 Ignore zero (0) data cells instead of NULL cells
21 -q
23 Run quietly
24 --overwrite
26 Allow output files to overwrite existing files
27 --verbose
29 Verbose module output
30 --quiet
32 Quiet module output
33 Parameters:
35 input=name
36 Name of input raster map
37 output=name
39 Name for output raster map
40 distances=float[,float,...]
42 Distance zone(s)
43 units=string
45 Units of distance
46 Options: meters,kilometers,feet,miles,nautmiles
47 Default: meters
48
50 r.buffer creates a new raster map layer showing buffer (a.k.a. "dis‐
51 tance" or "proximity") zones around all cells that contain non-NULL
52 category values in an existing raster map layer. The distances of buf‐
53 fer zones from cells with non-zero category values are user-chosen.
54 Suppose, for example, that you want to place buffer zones around roads.
55 This program could create the raster map layer shown below on the right
56 based on road information contained in the raster map layer shown on
57 the left.
58 000000000000000000000000 222233333333333333444444
59 111000000000000000000000 111222222222223333333333
60 000111111111100000000000 222111111111122223333333
61 000000001000011100000000 332222221222211122222222
62 000000001000000011111111 333333321233222211111111
63 000000001000000000000000 433333321233333222222222
64 000000001000000000000000 444443321233333333333333
65 000000001000000000000000 444443321233443333333333
66 000000001000000000000000 444443321233444444444444
67 Category 0: No roads
68 Category 1: Road location
69 Category 2: Buffer Zone 1 around roads
70 Category 3: Buffer Zone 2 around roads
71 Category 4: Buffer Zone 3 around roads
72
75 The user has the option of identifying up to 250 continuous zones. The
76 zones are identified by specifying the upper limit of each desired zone
77 (r.buffer assumes that 0 is the starting point). ("Continuous" is used
78 in the sense that each category zone's lower value is the previous
79 zone's upper value. The first buffer zone always has distance 0 as its
80 lower bound.) Buffer distances can be specified using one of five units
81 with the units parameter: meters, kilometers, feet, miles, and naut‐
82 miles (nautical miles).
83 Distances from cells containing the user-specified category values are
85 calculated using the "fromcell" method. This method locates each cell
86 that contains a category value from which distances are to be calcu‐
87 lated, and draws the requested distance rings around them. This method
88 works very fast when there are few cells containing the category values
89 of interest, but works slowly when there are numerous cells containing
90 the category values of interest spread throughout the area.
91 r.buffer measures distances from center of cell to center of cell using
93 Euclidean distance measure for planimetric locations (like UTM) and
94 using ellipsoidal geodesic distance measure for latitude/longitude
95 locations.
96 r.buffer calculates distance zones from all cells having non-NULL cate‐
98 gory values in the input map. If the user wishes to calculate distances
99 from only selected input map layer category values, the user should run
100 (for example) r.reclass prior to r.buffer, to reclass all categories
101 from which distance zones are not desired to be calculated into cate‐
102 gory NULL.
103 The -z flag can be used to ignore raster values of zero instead of NULL
105 values in the input raster map.
106
108 In the following example, the buffer zones would be (in the default
109 units of meters): 0-100, 101-200, 201-300, 301-400 and 401-500.
110 r.buffer input=roads output=roads.buf distances=100,200,300,400,500
112 Result:
113 r.category input=roads.buf
114 1 distances calculated from these locations
115 2 0-100 meters
116 3 100-200 meters
117 4 200-300 meters
118 5 300-400 meters
119 6 400-500 meters
120
123 g.region
124 r.cost
125 r.mapcalc
126 r.reclass
127 v.buffer
128
130 Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
131 James Westervelt, U.S. Army Construction Engineering Research Labora‐
132 tory
133 Last changed: $Date: 2008-02-19 21:18:46 +0100 (Tue, 19 Feb 2008) $
135 Full index
137 © 2003-2008 GRASS Development Team
139GRASS 6.3.0 r.buffer(1)