NAME
v.buffer - Create 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]
Flags:
- --overwrite
- Force overwrite of output files
Parameters:
- input=name
- Name of input vector map
- output=name
- Name for output vector map
- type=string[,string,...]
- Type
- Options: point,line,boundary,centroid,area
- Default: point,line,area
- layer=integer
- Layer number
- 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 with category of given field.
The tolerance parameter controls the number of vector segments being generated (the
smaller the value, the more vector segments are generated).
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
Note that attributes are not transferred (due to potential buffer overlap which cannot be
resolved automatically).
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 \
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
and 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: 2006/09/20 13:55:20 $
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