NAME
v.to.rast - Converts a binary GRASS vector map layer into a GRASS raster map layer.
SYNOPSIS
v.to.rast
v.to.rast help
v.to.rast input=string [layer=integer] output=string [use=string] [column=string] [value=float] [rows=integer]
Parameters:
- input=string
- vector input file
- layer=integer
- Layer number
- Default: 1
- output=string
- raster output file
- use=string
- Source of raster values:
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)
- Options: attr,cat,val,z
- Default: attr
- column=string
- Column name
- value=float
- Raster value
- 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.
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 col parameter or the value
parameter must be specified.
The col 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.
EXAMPLE
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
AUTHORS
Michael Shapiro,
U.S. Army Construction Engineering
Research Laboratory
Radim Blazek, ITC-Irst, Trento, Italy
Last changed: $Date: 2004/06/01 03:56:02 $
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