Provided by: grass-doc_7.6.1-2_all bug

NAME

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

KEYWORDS

       vector, conversion, raster, rasterization

SYNOPSIS

       v.to.rast
       v.to.rast --help
       v.to.rast  [-d]  input=name   [layer=string]    [type=string[,string,...]]    [cats=range]
       [where=sql_query]   output=name  use=string   [attribute_column=name]    [rgb_column=name]
       [label_column=name]      [value=float]      [memory=integer]     [--overwrite]    [--help]
       [--verbose]  [--quiet]  [--ui]

   Flags:
       -d
           Create densified lines (default: thin lines)
           All cells touched by the line will be set, not only those on the render path

       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       input=name [required]
           Name of input vector map
           Or data source for direct OGR access

       layer=string
           Layer number or name
           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.
           Default: 1

       type=string[,string,...]
           Input feature type
           Options: point, line, boundary, centroid, area
           Default: point,line,area

       cats=range
           Category values
           Example: 1,3,7-9,13

       where=sql_query
           WHERE conditions of SQL statement without ’where’ keyword
           Example: income < 1000 and population >= 10000

       output=name [required]
           Name for output raster map

       use=string [required]
           Source of raster values
           Options: attr, cat, val, z, dir
           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: line direction in degrees CCW from east (lines only)

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

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

       label_column=name
           Name of column used as raster category labels

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

       memory=integer
           Maximum memory to be used (in MB)
           Cache size for raster rows
           Default: 300

DESCRIPTION

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

NOTES

       In order to avoid unexpected results,  the  type  of  vector  features  should  always  be
       specified. The default is to convert all vector features, but if only e.g. areas should be
       converted use type=area rather than type=point,line,area.

       v.to.rast will only affect data in areas  lying  inside  the  boundaries  of  the  current
       geographic region.  A grid cell belongs to the area where the grid cell center falls into.

       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  - line direction in degrees counterclockwise from east (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.

       Line directions are given in degrees counterclockwise from east.

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

       The  -d  flag applies only to lines and boundaries, the default is to set only those cells
       on the render path (thin line).

       Boundaries (usually without categories) can be rasterized with
       v.to.rast type=boundary layer=-1 use=val

EXAMPLES

   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 input=vect_map output=raster_map attribute_column=SPEED type=line

   Calculate stream directions from a river vector map (Spearfish)
       v.to.rast input=streams output=streamsdir use=dir

   Calculate slope along path
       Using slope and aspect maps, compute slope along a bus route (use full NC sample dataset):
       g.region raster=elevation -p
       r.slope.aspect elevation=elevation slope=slope aspect=aspect
       # compute direction of the bus route
       v.to.rast input=busroute11 type=line output=busroute11_dir use=dir
       # extract steepest slope values and transform them into slope along path
       r.mapcalc "route_slope = if(busroute11, slope)"
       r.mapcalc "route_slope_dir = abs(atan(tan(slope) * cos(aspect - busroute11_dir)))"
       Slope in degrees along bus route

   Convert a vector polygon map to raster including descriptive labels (Spearfish)
       v.to.rast input=fields output=myfields use=attr attribute_column=cat label_column=label
       r.category myfields

   Convert vector points to raster with raster cell binning
       In this example, the number of schools per raster cell are counted (North Carolina  sample
       dataset):
       g.copy vector=schools_wake,myschools_wake
       # set computation region for raster binning
       g.region vector=myschools_wake res=5000 -p -a
       # add new column for counting
       v.db.addcolumn myschools_wake column="value integer"
       v.db.update myschools_wake column=value value=1
       # verify attributes
       v.db.select myschools_wake column=cat,value
       v.out.ascii input=myschools_wake output=- column=value
       # export and import on the fly, use 4th column (value) as input
       v.out.ascii input=myschools_wake output=- column=value | r.in.xyz input=- \
                   z=4 output=schools_wake_aggreg method=sum
       d.mon wx0
       d.rast schools_wake_aggreg
       d.vect schools_wake
       d.grid 5000
       Number of schools per raster cell

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: 2017-03-16 04:03:42 +0100 (Thu, 16 Mar 2017) $

SOURCE CODE

       Available at: v.to.rast source code (history)

       Main index | Vector index | Topics index | Keywords index | Graphical index | Full index

       © 2003-2019 GRASS Development Team, GRASS GIS 7.6.1 Reference Manual