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v.buffer.1grass

NAME

v.buffer

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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