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=memory in MB

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

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¶

In this example, the ZIP code vector map is rasterized (North Carolina sample dataset):

# rasterize ZIP codes at 50m raster resolution
g.region vector=zipcodes_wake res=50 -ap
# vector to raster conversion, with category labels
v.to.rast input=zipcodes_wake output=myzipcodes use=attr attribute_column="ZIPNUM" label_column="NAME"

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