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v.buffer

NAME

v.buffer - Creates a buffer around features of given type (areas must contain centroid).

KEYWORDS

vector

SYNOPSIS

v.buffer
v.buffer help
v.buffer input=name output=name [type=string[,string,...]] [layer=integer] [buffer=float] [bufcol=string] [scale=float] [tolerance=float] [debug=string] [--overwrite] [--verbose] [--quiet]

Flags:

--overwrite

Allow output files to overwrite existing files

--verbose

Verbose module output

--quiet

Quiet module output

Parameters:

input=name

Name of input vector map

output=name

Name for output vector map

type=string[,string,...]

Type
Feature type(s)
Options: point,line,boundary,centroid,area
Default: point,line,area

layer=integer

Layer number
A single vector map can be connected to multiple database tables. This number determines which table to use.
Default: 1

buffer=float

Buffer distance in map units

bufcol=string

Attribute 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

debug=string

Stop the process at a certain stage
Options: buffer,clean

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

Attributes are not transferred due to potential buffer overlap, which cannot be resolved automatically.

EXAMPLES

Buffer around input lines

v.buffer input=map output=buffer type=line buffer=100

Circles around input points

v.buffer input=pointsmap output=circles type=point buffer=1000

Non-overlapping circles around input points with attribute transfer

v.buffer input=archsites output=circles type=point buffer=200
# change original points to centroids:
v.type in=archsites out=archcentroids type=point,centroid
# patch circles and centroids:
v.patch in=archcentroids,circles out=circles_db
# attach attributes, either use
# db.copy ...
# or link to the original table:
v.db.connect map=circles_db table=archsites field=1 key=cat driver=dbf rs
database='$GISDBASE/$LOCATION_NAME/$MAPSET/dbf'

BUGS

For some data v.buffer can produce strange results, especially if the buffer size is bigger than input features. Usually you can solve the problem if you run v.buffer more times with smaller buffer.

The bufcol dynamic buffer distance parameter has problems cleaning complex features. (holes left filled, etc.) If you experience problems, try running v.buffer multiple times with a single buffer distance, patch the results with v.patch and remove any overlaps with v.extract -d.

SEE ALSO

r.buffer, v.extract, v.type, v.patch, v.db.connect

AUTHOR

Radim Blazek

Last changed: $Date: 2007-06-04 11:26:16 +0200 (Mon, 04 Jun 2007) $

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