.TH v.to.rast 1grass "" "GRASS 6.4.4" "Grass User's Manual"
.SH NAME
\fI\fBv.to.rast\fR\fR  - Converts (rasterize) a vector map into a raster map.
.SH KEYWORDS
vector, raster, conversion
.SH SYNOPSIS
\fBv.to.rast\fR
.br
\fBv.to.rast help\fR
.br
\fBv.to.rast input\fR=\fIname\fR  [\fBlayer\fR=\fIinteger\fR]   [\fBtype\fR=\fIstring\fR[,\fIstring\fR,...]]  \fBoutput\fR=\fIname\fR \fBuse\fR=\fIstring\fR  [\fBcolumn\fR=\fIname\fR]   [\fBrgbcolumn\fR=\fIname\fR]   [\fBlabelcolumn\fR=\fIname\fR]   [\fBvalue\fR=\fIfloat\fR]   [\fBrows\fR=\fIinteger\fR]   [\-\-\fBoverwrite\fR]  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR] 
.SS Flags:
.IP "\fB\-\-overwrite\fR" 4m
.br
Allow output files to overwrite existing files
.IP "\fB\-\-verbose\fR" 4m
.br
Verbose module output
.IP "\fB\-\-quiet\fR" 4m
.br
Quiet module output
.PP
.SS Parameters:
.IP "\fBinput\fR=\fIname\fR" 4m
.br
Name of input vector map
.IP "\fBlayer\fR=\fIinteger\fR" 4m
.br
Layer number
.br
A single vector map can be connected to multiple database tables. This number determines which table to use.
.br
Default: \fI1\fR
.IP "\fBtype\fR=\fIstring[,\fIstring\fR,...]\fR" 4m
.br
Feature type
.br
Options: \fIpoint,line,area\fR
.br
Default: \fIpoint,line,area\fR
.IP "\fBoutput\fR=\fIname\fR" 4m
.br
Name for output raster map
.IP "\fBuse\fR=\fIstring\fR" 4m
.br
Source of raster values
.br
Options: \fIattr,cat,val,z,dir\fR
.br
Default: \fIattr\fR
.br
\fBattr\fR: read values from attribute table
.br
\fBcat\fR: use category values
.br
\fBval\fR: use value specified by value option
.br
\fBz\fR: use z coordinate (points or contours only)
.br
\fBdir\fR: output as flow direction (lines only)
.IP "\fBcolumn\fR=\fIname\fR" 4m
.br
Name of column for 'attr' parameter (data type must be numeric)
.IP "\fBrgbcolumn\fR=\fIname\fR" 4m
.br
Name of color definition column (with RRR:GGG:BBB entries)
.IP "\fBlabelcolumn\fR=\fIname\fR" 4m
.br
Name of column used as raster category labels
.IP "\fBvalue\fR=\fIfloat\fR" 4m
.br
Raster value (for use=val)
.br
Default: \fI1\fR
.IP "\fBrows\fR=\fIinteger\fR" 4m
.br
Number of rows to hold in memory
.br
Default: \fI4096\fR
.PP
.SH DESCRIPTION
\fIv.to.rast\fR transforms GRASS vector map layers into GRASS raster map
layer format. Optionally, attributes can be converted into raster category
labels.
.SH NOTES
\fIv.to.rast\fR will only affect data in areas lying
inside the boundaries of the current geographic region.
Before running \fIv.to.rast\fR, the user should
therefore ensure that the current geographic region is
correctly set and that the region resolution is at the
desired level.
.PP
Either the \fI\fBcolumn\fR\fR parameter or the \fI\fBvalue\fR\fR
parameter must be specified.  The \fI\fBuse\fR\fR option may be 
specified alone when using the \fIdir\fR option.
.PP
\fI\fBuse\fR\fR options are:
.RS
.IP
\fIattr\fR - read values from attribute table (default)
.IP
\fIcat\fR  - read values from category
.IP
\fIval\fR  - use value specified by \fI\fBvalue\fR\fR option
.IP
\fIz\fR    - use z coordinate (points or contours only)
.IP
\fIdir\fR  - output as flow direction in degrees (lines only)
.RE
.PP
The \fI\fBcolumn\fR\fR parameter uses an existing column from the vector map
database table as the category value in the output raster map. Existing table 
columns can be shown by using \fIdb.describe\fR.
.PP
An empty raster map layer will be created if the vector map layer has not
been assigned category/attribute labels (e.g., through use of 
v.category option=add). 
.PP
Otherwise:
.RS
.IP
Labeled areas and/or centroids will produce filled raster coverages with edges 
that straddle the original area boundary \fBas long as the boundary is NOT 
labeled\fR.
.br
(Use v.category option=del type=boundary to remove.)
.IP
Labeled lines and boundaries will produce lines of raster cells which touch the 
original vector line. This tends to be more aggressive than area-only conversions.
.IP
Points and orphaned centroids will be converted into single cells on the
resultant raster map.
.RE
.PP
.PP
\fBFlow directions\fR are given in degrees counterclockwise from east.
.PP
.PP
Raster category labels are supported for all of \fIuse=\fR except \fIuse=z\fR.
.SH EXAMPLES
\fI1. Convert a vector map and use column SPEED from attribute table\fR
.br
\fC
.DS
.br
db.describe \-c table=vect_map
.br
.br
ncols:3
.br
Column 1: CAT
.br
Column 2: SPEED
.br
Column 3: WIDTH 
.br
.DE
\fR
\fC
.DS
.br
v.to.rast in=vect_map out=raster_map col=SPEED
.br
.DE
\fR
.PP
.PP
\fI2. Calculate stream directions from a river vector map (Spearfish)\fR
.br
\fC
.DS
.br
v.to.rast in=streams out=streamsdir use=dir
.br
.DE
\fR
.PP
.PP
\fI3. Convert a vector polygon map to raster including descriptive labels (Spearfish)\fR
.br
\fC
.DS
.br
v.to.rast in=fields out=myfields use=attr col=cat labelcol=label
.br
r.category myfields
.br
.DE
\fR
.SH SEE ALSO
\fI
db.describe,
v.category
\fR
.br
.SH AUTHORS
Original code: Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
.br
GRASS 6.0 updates: Radim Blazek, ITC-irst, Trento, Italy
.br
Stream directions: Jaro Hofierka and Helena Mitasova
.br
GRASS 6.3 code cleanup and label support: Brad Douglas
.PP
.PP
\fILast changed: $Date: 2011-11-08 12:29:50 +0100 (Tue, 08 Nov 2011) $\fR
.PP
Full index
.PP
© 2003-2014 GRASS Development Team