NAME
v.buffer - Creates a buffer around vector features of given type.
KEYWORDS
vector, geometry, buffer
SYNOPSIS
v.buffer
v.buffer help
v.buffer [-sct] input=name layer=string [type=string[,string,...]] output=name [distance=float] [minordistance=float] [angle=float] [bufcolumn=name] [scale=float] [tolerance=float] [--overwrite] [--verbose] [--quiet]
Flags:
- -s
- Make outside corners straight
- -c
- Don't make caps at the ends of polylines
- -t
- Transfer categories and attributes
- --overwrite
- Allow output files to overwrite existing files
- --verbose
- Verbose module output
- --quiet
- Quiet module output
Parameters:
- input=name [required]
- Name of input vector map
- Or data source for direct OGR access
- layer=string [required]
- Layer number or name ('-1' for all layers)
- A single vector map can be connected to multiple database tables. This number determines which table to use. When used with direct OGR access this is the layer name.
- Default: -1
- type=string[,string,...]
- Feature type
- Options: point, line, boundary, centroid, area
- Default: point,line,area
- output=name [required]
- Name for output vector map
- distance=float
- Buffer distance along major axis in map units
- minordistance=float
- Buffer distance along minor axis in map units
- angle=float
- Angle of major axis in degrees
- Default: 0
- bufcolumn=name
- Name of column to use for buffer distances
- scale=float
- Scaling factor for attribute column values
- Default: 1.0
- tolerance=float
- Maximum distance between theoretical arc and polygon segments as multiple of buffer
- Default: 0.01
DESCRIPTION
v.buffer creates a buffer around features of given type
, which have a category in the given layer. The
tolerance controls the number of vector segments being generated
(the smaller the value, the more vector segments are generated).
NOTES
Internal buffers for areas can be generated with negative distiance
values (GRASS must be compiled with GEOS).
Categories and attributes can be transferred with the t flag.
The resulting buffer areas can have multiple categories, and multiple
buffer areas can have the same category. The buffer for the input
feature with category X can thus be retrieved by selecting all buffer
areas with category X (see example below).
EXAMPLES
All examples are based on the North Carolina sample dataset.
Buffer around input lines
v.buffer input=roadsmajor output=roadsmajor_buffer type=line distance=100
Circles around input points
v.buffer input=hospitals output=hospitals_circled type=point distance=1000
Circles around input points with attribute transfer
v.buffer input=hospitals output=hospitals_circled type=point distance=1000 -t
# display buffer around hospital with category 36,
# this buffer is composed of several areas:
d.vect map=hospitals_circled type=area layer=1 cats=36
# extract this buffer, dissolving boundaries
v.extract in=hospitals_circled out=hospital_36_circled layer=1 cats=36 -d
SEE ALSO
r.buffer,
v.extract,
v.type,
v.patch,
v.db.connect
AUTHORS
Radim Blazek
Rewritten by Rosen Matev (with support through the
Google Summer of Code program 2008)
Rewritten by Markus Metz (2011, 2012)
Last changed: $Date: 2012-05-01 01:34:25 -0700 (Tue, 01 May 2012) $
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