NAME

       v.to.rast  - Converts (rasterize) a vector map into a raster map.

KEYWORDS

       vector, raster, conversion

SYNOPSIS

       v.to.rast
       v.to.rast help
       v.to.rast input=name  [layer=integer]   [type=string[,string,...]]  output=name use=string
       [column=name]    [rgbcolumn=name]    [labelcolumn=name]    [value=float]    [rows=integer]
       [--overwrite]  [--verbose]  [--quiet]

   Flags:
       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name
           Name of input vector map

       layer=integer
           Layer number
           A  single  vector  map  can  be  connected  to  multiple  database tables. This number
           determines which table to use.
           Default: 1

       type=string[,string,...]
           Feature type
           Options: point,line,area
           Default: point,line,area

       output=name
           Name for output raster map

       use=string
           Source of raster values
           Options: attr,cat,val,z,dir
           Default: attr
           attr: read values from attribute table
           cat: use category values
           val: use value specified by value option
           z: use z coordinate (points or contours only)
           dir: output as flow direction (lines only)

       column=name
           Name of column for 'attr' parameter (data type must be numeric)

       rgbcolumn=name
           Name of color definition column (with RRR:GGG:BBB entries)

       labelcolumn=name
           Name of column used as raster category labels

       value=float
           Raster value (for use=val)
           Default: 1

       rows=integer
           Number of rows to hold in memory
           Default: 4096

DESCRIPTION

       v.to.rast transforms  GRASS  vector  map  layers  into  GRASS  raster  map  layer  format.
       Optionally, attributes can be converted into raster category labels.

NOTES

       v.to.rast  will  only  affect  data  in  areas  lying inside the boundaries of the current
       geographic region.  Before running v.to.rast, the user should therefore  ensure  that  the
       current  geographic  region  is  correctly  set  and  that the region resolution is at the
       desired level.

       Either the column parameter or the value parameter must be specified.  The use option  may
       be specified alone when using the dir option.

       use options are:

                     attr - read values from attribute table (default)

                     cat  - read values from category

                     val  - use value specified by value option

                     z    - use z coordinate (points or contours only)

                     dir  - output as flow direction in degrees (lines only)

       The  column  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
       db.describe.

       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).

       Otherwise:

                     Labeled areas and/or centroids will produce  filled  raster  coverages  with
                     edges  that  straddle  the original area boundary as long as the boundary is
                     NOT labeled.
                     (Use v.category option=del type=boundary to remove.)

                     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.

                     Points and orphaned centroids will be converted into  single  cells  on  the
                     resultant raster map.

       Flow directions are given in degrees counterclockwise from east.

       Raster category labels are supported for all of use= except use=z.

EXAMPLES

       1. Convert a vector map and use column SPEED from attribute table

       db.describe -c table=vect_map
       ncols:3
       Column 1: CAT
       Column 2: SPEED
       Column 3: WIDTH

       v.to.rast in=vect_map out=raster_map col=SPEED

       2. Calculate stream directions from a river vector map (Spearfish)

       v.to.rast in=streams out=streamsdir use=dir

       3. Convert a vector polygon map to raster including descriptive labels (Spearfish)

       v.to.rast in=fields out=myfields use=attr col=cat labelcol=label
       r.category myfields

SEE ALSO

        db.describe, v.category

AUTHORS

       Original code: Michael Shapiro, U.S. Army Construction Engineering Research Laboratory
       GRASS 6.0 updates: Radim Blazek, ITC-irst, Trento, Italy
       Stream directions: Jaro Hofierka and Helena Mitasova
       GRASS 6.3 code cleanup and label support: Brad Douglas

       Last changed: $Date: 2011-11-08 03:29:50 -0800 (Tue, 08 Nov 2011) $

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       © 2003-2013 GRASS Development Team