NAME¶
v.buffer - Creates a buffer around vector features of given type.
KEYWORDS¶
vector, buffer, geometry
SYNOPSIS¶
v.buffer
v.buffer help
v.buffer [-
sct]
input=
name
[
layer=
integer] [
cats=
range]
[
where=
sql_query] [
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
-
Name of input vector map
- layer=integer
-
Layer number
A single vector map can be connected to multiple database tables. This
number determines which table to use.
Default: 1
- cats=range
-
Category values
Example: 1,3,7-9,13
- where=sql_query
-
WHERE conditions of SQL statement without 'where' keyword
Example: income = 10000
- type=string[,string,...]
-
Feature type
Options: point,line,boundary,centroid,area
Default: point,line,area
- output=name
-
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 distance values
("inward buffer" or "negative buffer"). Attributes are not
transferred due to potential buffer overlap, which cannot be resolved
automatically.
Buffers for lines and areas are generated using the algorithms from the GEOS
library.
EXAMPLES¶
All examples are based on the North Carolina sample dataset.
v.buffer input=roadsmajor output=roadsmajor_buffer type=line distance=100
Buffer of 100m along the "roadsmajor" lines (map subset, original
center line shown in black)
v.buffer input=hospitals output=hospitals_circled type=point distance=2000
Buffer of 2000m around the "hospitals" points (map subset, original
points shown in black, new area centroids in red)
# copy map to current mapset (for easier DB linking)
g.copy vect=hospitals,myhospitals
v.buffer input=myhospitals output=circles type=point distance=2000
# change original points to centroids:
v.type in=myhospitals out=hospital_centroids type=point,centroid
# patch circles and centroids:
v.patch in=hospital_centroids,circles out=circles_db
# attach attributes, either use db.copy or link to the original table:
v.db.connect map=circles_db table=myhospitals layer=1 key=cat driver=dbf \
database='$GISDBASE/$LOCATION_NAME/$MAPSET/dbf'
v.db.select circles_db
v.buffer input=lakes output=lakes_buffer type=area distance=100
Buffer of 100m around the "lakes" polygons (map subset, original areas
shown in black)
REFERENCE¶
SEE ALSO¶
r.buffer, v.parallel, 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: 2014-04-30 18:19:24 +0200 (Wed, 30 Apr 2014) $
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