v.overlay(1)

NAME
v.overlay

DESCRIPTION
v.overlay allows the user to overlay two vector area maps. The resulting output map has a merged attribute-table. The origin column-names have a prefix (a_ and b_) which results from the ainput- and binput-map.

NOTES
Currently only areas are supported for the operators or and xor! See also v.select. The operator defines what kind of operation will be done. Features are written to output, if the result of an operation 'ainput operator binput' is true.

Attributes of the tables from ainput and binput are joined into a new table linked to the output maps new cat-column.

EXAMPLE POLYGON TO POLYGON UNION
v.overlay ainput=lake binput=province output=lakeXprovince operator=or

EXAMPLE LINE TO POLYGON CLIPPING
Using the North Carolina sample dataset, we clip the roads map to the area of city of Raleigh:
g.region vect=zipcodes_wake
# extract Raleigh city
v.extract in=zipcodes_wake out=raleigh \
            where="ZIPNAME = 'RALEIGH'"
# clip road network to city polygon:
v.overlay ainput=roadsmajor atype=line binput=raleigh \
            out=roadsmajor_raleigh operator=and
    | v.overlay: Line to polygon clipping

SEE ALSO
v.db.connect, v.select, g.copy

AUTHORS
Radim Blazek, ITC-Irst, Trento, Italy

Last changed: $Date: 2011-11-08 12:29:50 +0100 (Tue, 08 Nov 2011) $

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