Ubuntu Manpage: r.buffer - Creates a raster map showing buffer zones surrounding cells that contain non-NULL category

Provided by: grass-doc_7.8.2-1build3_all

NAME

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

KEYWORDS

       raster, buffer

SYNOPSIS

       r.buffer
       r.buffer --help
       r.buffer  [-z]  input=name  output=name   distances=float[,float,...]    [units=string]     [--overwrite]
       [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       -z
           Ignore zero (0) data cells instead of NULL cells

       --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:
       input=name [required]
           Name of input raster map

       output=name [required]
           Name for output raster map

       distances=float[,float,...] [required]
           Distance zone(s)

       units=string
           Units of distance
           Options: meters, kilometers, feet, miles, nautmiles
           Default: meters

DESCRIPTION

       r.buffer  creates  a  new  raster  map showing buffer (a.k.a. "distance" or "proximity") zones around all
       cells that contain non-NULL category values in an existing raster map. The distances of buffer zones from
       cells with non-zero category values are user-chosen and must be positive value(s).  Suppose, for example,
       that you want to place buffer zones around roads.  This program could create the raster map  shown  below
       on the right based on road information contained in the raster map shown on the left.
             000000000000000000000000 222233333333333333444444
             111000000000000000000000 111222222222223333333333
             000111111111100000000000 222111111111122223333333
             000000001000011100000000 332222221222211122222222
             000000001000000011111111 333333321233222211111111
             000000001000000000000000 433333321233333222222222
             000000001000000000000000 444443321233333333333333
             000000001000000000000000 444443321233443333333333
             000000001000000000000000 444443321233444444444444
             Category 0: No roads
             Category 1: Road location
             Category 2: Buffer Zone 1 around roads
             Category 3: Buffer Zone 2 around roads
             Category 4: Buffer Zone 3 around roads

NOTES

The user has the option of identifying up to 250 continuous zones. The zones are identified by
specifying the upper limit of each desired zone (r.buffer assumes that 0 is the starting point).
"Continuous" is used in the sense that each category zone’s lower value is the previous zone’s upper
value. The first buffer zone always has distance 0 as its lower bound. Buffer distances can be specified
using one of five units with the units parameter.

Distances from cells containing the user-specified category values are calculated using the "fromcell"
method. This method locates each cell that contains a category value from which distances are to be
calculated, and draws the requested distance rings around them. This method works very fast when there
are few cells containing the category values of interest, but works slowly when there are numerous cells
containing the category values of interest spread throughout the area.

r.buffer measures distances from center of cell to center of cell using Euclidean distance measure for
planimetric locations (like UTM) and using ellipsoidal geodesic distance measure for latitude/longitude
locations.

r.buffer calculates distance zones from all cells having non-NULL category values in the input map. If
the user wishes to calculate distances from only selected input map category values, the user should run
(for example) r.reclass prior to r.buffer, to reclass all categories from which distance zones are not
desired to be calculated into category NULL.

The -z flag can be used to ignore raster values of zero instead of NULL values in the input raster map.

When working with massive raster regions consider the r.buffer.lowmem module if RAM use becomes a
problem. The lowmem version can be > 40x slower, but will work with minimal memory requirements. The
classic r.buffer should be able to deal with raster maps of 32000x32000 size on a system with 1 GB RAM,
and rasters of 90000x90000 on a system with 8 GB RAM without going into swap.

EXAMPLE

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

AUTHORS

       Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
       James Westervelt, U.S. Army Construction Engineering Research Laboratory

SOURCE CODE

       Available at: r.buffer source code (history)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual