.TH v.centroids 1grass "" "GRASS 7.8.5" "GRASS GIS User's Manual"
.SH NAME
\fI\fBv.centroids\fR\fR  \- Adds missing centroids to closed boundaries.
.SH KEYWORDS
vector, centroid, area
.SH SYNOPSIS
\fBv.centroids\fR
.br
\fBv.centroids \-\-help\fR
.br
\fBv.centroids\fR \fBinput\fR=\fIname\fR \fBoutput\fR=\fIname\fR  [\fBoption\fR=\fIstring\fR]   [\fBlayer\fR=\fIstring\fR]   [\fBcat\fR=\fIinteger\fR]   [\fBstep\fR=\fIinteger\fR]   [\-\-\fBoverwrite\fR]  [\-\-\fBhelp\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR]  [\-\-\fBui\fR]
.SS Flags:
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-help\fR" 4m
.br
Print usage summary
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.IP "\fB\-\-ui\fR" 4m
.br
Force launching GUI dialog
.SS Parameters:
.IP "\fBinput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name of input vector map
.br
Or data source for direct OGR access
.IP "\fBoutput\fR=\fIname\fR \fB[required]\fR" 4m
.br
Name for output vector map
.IP "\fBoption\fR=\fIstring\fR" 4m
.br
Action to be taken
.br
Options: \fIadd\fR
.br
Default: \fIadd\fR
.IP "\fBlayer\fR=\fIstring\fR" 4m
.br
Layer number or name
.br
Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
.br
Default: \fI1\fR
.IP "\fBcat\fR=\fIinteger\fR" 4m
.br
Category number starting value
.br
Default: \fI1\fR
.IP "\fBstep\fR=\fIinteger\fR" 4m
.br
Category increment
.br
Default: \fI1\fR
.SH DESCRIPTION
GRASS defines vector areas as composite entities consisting of a set of
closed boundaries and a centroid. The attribute information associated
with that area is linked to the centroid. The \fIv.centroids\fR module
adds centroids to closed boundaries in the \fBinput\fR file and assigns a
category number to them. The starting value as well as the increment size
may be set using optional parameters.
.PP
Multiple attributes may be linked to a single vector entity through
numbered fields referred to as layers. Refer to \fIv.category\fR
for more details, as \fIv.centroids\fR is simply a frontend to that
module.
.PP
The boundary itself is often stored without any category reference as it
can mark the border between two adjacent areas. Thus it would be ambiguous
as to which feature the attribute would belong. In some cases it may, for
example, represent a road between two parcels of land. In this case it
is entirely appropriate for the boundary to contain category information.
.SH EXAMPLES
Create an area from a closed line using North Carolina sample dataset:
.br
.nf
\fC
v.type input=busroute11 output=busroute11_boundary from_type=line to_type=boundary
v.centroids input=busroute11_boundary output=busroute11_area
\fR
.fi
.br
\fIFigure: Creating area from closed line\fR
.SH SEE ALSO
\fI
v.category
\fR
.SH AUTHORS
module: M. Hamish Bowman, Dept. Marine Science, Otago University, New Zealand
.br
help page: Trevor Wiens
.SH SOURCE CODE
.PP
Available at: v.centroids source code (history)
.PP
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.PP
© 2003\-2020
GRASS Development Team,
GRASS GIS 7.8.5 Reference Manual