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NAME

KEYWORDS

SYNOPSIS

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

NOTES

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

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

AUTHORS

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

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