NAME

v.overlay - Overlay 2 vector maps.

SYNOPSIS

v.overlay
v.overlay help
v.overlay [-t] ainput=string [atype=string[,string,...]] [afield=integer] binput=string [btype=string[,string,...]] [bfield=integer] output=string [operator=string] [ofield=integer[,integer,...]]

Flags:

-t
Do not create attribute table.

Parameters:

ainput=string
Name of input vector
atype=string
Select type: point, line, boundary, centroid or area
Options: line,area
Default: area
afield=integer
Field value
Default: 1
binput=string
Name of input vector
btype=string
Select type: point, line, boundary, centroid or area
Options: area
Default: area
bfield=integer
Field value
Default: 1
output=string
Name of output vector
operator=string
Operator defines features written to output vector. Feature is written to output if the result of operation 'ainput operator binput' is true. Input feature is considered to be true, if category of given field is defined.
and : also known as 'intersection' in GIS
or : also known as 'union' in GIS (only for atype=area)
not : features from ainput not overlayed by features from binput
xor : features from either ainput or binput but not those from ainput overlayed by binput (only for atype=area)
Options: and,or,not,xor
Default: or
ofield=integer
Output field for new category, ainput and binput. If 0 or not given, the category is not written.
Default: 1,2,3

DESCRIPTION

v.overlay allows the user to overlay to vector area maps. There are 3 links attached to features in output map,

NOTES

Currently only areas are supported!

Joining attribute tables from ainput and binput into a new table linked to the output map is not implemented yet.

To query categories from ainput and/or binput it is necessary to link the related tables to fields with v.db.connect.

v.db.connect map=outputmap table=ainput.dbf field=2
v.db.connect map=outputmap table=binput.dbf field=3

Attention: Removing the output map will also delete all tables linked to it! Therefore it is advisable to copy tables from ainput and binput first and connect the copied tables to the output map.

EXAMPLE

v.overlay ainput=lake binput=province output=lakeXprovince

SEE ALSO

v.db.connect
g.copy

AUTHORS

Radim Blazek, ITC-Irst, Trento, Italy

Last changed: $Date: 2004/09/17 15:15:50 $


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