v.colors.1grass man page

v.colors — Creates/modifies the color table associated with a vector map.


vector, color table


v.colors --help
v.colors [-rwlngac] map=name [layer=string] use=string [column=name] [range=min,max] [color=style] [raster=name] [raster_3d=name] [rules=name] [rgb_column=name] [--help] [--verbose] [--quiet] [--ui]


Remove existing color table
Only write new color table if it does not already exist
List available rules then exit
Invert colors
Logarithmic scaling
Logarithmic-absolute scaling
Convert color rules from RGB values to color table
Option ’rgb_column’ with valid RGB values required
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


map=name [required]
Name of vector map
Or data source for direct OGR access
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
use=string [required]
Source values
Options: attr, cat, z
Default: cat
attr: read values from attribute table (requires <column> option)
cat: use category values
z: use z coordinate (3D points or centroids only)
Name of column containing numeric data
Required for use=attr
Manually set range (refers to ’column’ option)
Ignored when ’rules’ given
Name of color table
Options: aspect, aspectcolr, bcyr, bgyr, blues, byg, byr, celsius, corine, curvature, differences, elevation, etopo2, evi, fahrenheit, gdd, greens, grey, grey.eq, grey.log, grey1.0, grey255, gyr, haxby, kelvin, ndvi, ndwi, oranges, population, population_dens, precipitation, precipitation_daily, precipitation_monthly, rainbow, ramp, random, reds, rstcurv, ryb, ryg, sepia, slope, srtm, srtm_plus, terrain, wave
aspect: aspect oriented grey colors
aspectcolr: aspect oriented rainbow colors
bcyr: blue through cyan through yellow to red
bgyr: blue through green through yellow to red
blues: white to blue
byg: blue through yellow to green
byr: blue through yellow to red
celsius: blue to red for degree Celsius temperature
corine: EU Corine land cover colors
curvature: for terrain curvatures (from v.surf.rst and r.slope.aspect)
differences: differences oriented colors
elevation: maps relative ranges of raster values to elevation color ramp
etopo2: colors for ETOPO2 worldwide bathymetry/topography
evi: enhanced vegetative index colors
fahrenheit: blue to red for Fahrenheit temperature
gdd: accumulated growing degree days
greens: white to green
grey: grey scale
grey.eq: histogram-equalized grey scale
grey.log: histogram logarithmic transformed grey scale
grey1.0: grey scale for raster values between 0.0-1.0
grey255: grey scale for raster values between 0-255
gyr: green through yellow to red
haxby: relative colors for bathymetry or topography
kelvin: blue to red for temperature in Kelvin scale
ndvi: Normalized Difference Vegetation Index colors
ndwi: Normalized Difference Water Index colors
oranges: white to orange
population: color table covering human population classification breaks
population_dens: color table covering human population density classification breaks
precipitation: precipitation color table (0..2000mm)
precipitation_daily: precipitation color table (0..1000mm)
precipitation_monthly: precipitation color table (0..1000mm)
rainbow: rainbow color table
ramp: color ramp
random: random color table
reds: white to red
rstcurv: terrain curvature (from r.resamp.rst)
ryb: red through yellow to blue
ryg: red through yellow to green
sepia: yellowish-brown through to white
slope: r.slope.aspect-type slope colors for raster values 0-90
srtm: color palette for Shuttle Radar Topography Mission elevation
srtm_plus: color palette for Shuttle Radar Topography Mission elevation (with seafloor colors)
terrain: global elevation color table covering -11000 to +8850m
wave: color wave
Raster map from which to copy color table
3D raster map from which to copy color table
Path to rules file
"-" to read rules from stdin
Name of color column to populate RGB values
If not given writes color table


v.colors allows creating or modifying color table associated with a vector map similarly to r.colors for raster maps.

Color rules are built from features category values (use=cat) or numeric data column (use=attr) defined by column option. For 3D vector maps is allowed to define color rules based on points or centroids z-coordinate (use=z). 3D vector lines are not supported.

The raster option allows user to specify a raster map from which to copy the color table, similarly raster_3d option for 3D raster map.

The rules color table type will cause v.colors to read color table specifications from given file and will build the color table accordingly. See r.colors manual page for details.

If the user specifies the -w flag, the current color table file for the input map will not be overwritten. This means that the color table is created only if the vector map does not already have a color table. If this option is not specified, the color table will be created if one does not exist, or modified if it does.

Alternatively the color rules can be stored in a string column (rgb_column) by saving the RRR:GGG:BBB values suitable for use with d.vect.


For vector maps with a large number of features it’s more convenient to store color rules in an attribute column (given by rgb_column) rather then in a color table file. Reading color tables with more then 1000 items is slow.


Define color table based on categories

Define color table wave based on categories from layer 1

v.colors map=soils_general layer=1 color=wave

Define color table based on attribute values

Define color table ryg based on values from attribute column AREA. Attribute table is linked to layer 1.

v.to.db map=soils_general layer=1 option=area column=AREA
v.colors map=soils_general layer=1 color=wave use=attr column=AREA

Define color table stored as RGB values in attribute table

Write color values to the attribute table (column GRASSRGB) instead of creating color table.

v.colors map=soils_general layer=1 color=wave use=attr column=AREA rgb_column=GRASSRGB
# See some GRASSRGB values:
v.db.select map=soils_general where="cat < 4"

Convert RGB attribute values into color table

Convert existing RGB values to color table rules.

v.colors -c map=soils_general rgb_column=GRASSRGB

Note that in this case the vector map has a proper color table assigned (check by v.colors.out) together with GRASSRGB attribute column. Also note that color table is preferred over RGB values stored in attribute table.

Remove existing color table

Existing color table can be removed by -r flag.

v.colors -r map=soils_general

Before removing color table you can store color rules to the file by v.colors.out and later to assign by rules option.

v.colors.out map=soils_general rules=soils.colr
v.colors map=soils_general rules=soils.colr

To drop RGB column use v.db.dropcolumn.

v.db.dropcolumn map=soils_general column=GRASSRGB

See Also

d.vect, r.colors, r.colors.out, r3.colors, r3.colors.out, v.colors.out

See also wiki page Color tables (from GRASS User Wiki)

ColorBrewer is an online tool designed to help people select good color schemes for maps and other graphics.


Martin Landa, OSGeoREL, Czech Technical University in Prague, Czech Republic

Last changed: $Date: 2015-02-13 16:16:22 +0100 (Fri, 13 Feb 2015) $

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