NAME
d.his - Produces and displays a raster map layer combining
hue, intensity, and saturation (his) values
from user-specified input raster map layers.
(GRASS Display Program)
SYNOPSIS
d.his
d.his help
d.his [-o] h_map=name
[i_map=name]
[s_map=name]
[output=name]
DESCRIPTION
his stands for hue, intensity, and saturation.
This program produces a raster map layer providing a
visually pleasing combination of hue, intensity, and
saturation values from two or three user-specified raster
map layers.
The human brain automatically interprets the vast amount of
visual information available according to basic rules.
Color, or hue, is used to categorize objects.
Shading, or intensity, is interpreted as
three-dimensional texturing. Finally, the degree of
haziness, or saturation, is associated with
distance or depth. This program allows data from up to
three raster map layers to be combined into one new raster
map layer which retains the original information in terms
of hue, intensity, and saturation.
OPTIONS
This program can be run non-interactively or
interactively. It will run non-interactively if the user
specifies on the command line the name of a map containing
hue values (h_map), and the name(s) of map(s)
containing intensity values (i_map) and/or
saturation values (s_map). If the user also names
an output map (output) on the command line, the
combined hue, saturation, and intensity values will be
saved as a raster map layer in the user's current mapset;
otherwise, the resulting image will only be displayed in
the active display frame on the graphics monitor.
Alternately, the user can run the program interactively by
typing d.his without naming parameter values on the
command line. In this case, the program will prompt the
user for parameter values using the standard GRASS
parser interface.
Flags:
- -o
- Overwrite output map.
Parameters:
- h_map=name
- Name of input raster map layer to be used for HUE values.
- i_map=name
- Name of input raster map layer to be used for INTENSITY values.
- s_map=name
- Name of input raster map layer to be used for SATURATION values.
- output=name
- Name of the output raster map layer combining hue,
intensity, and saturation values from input layers.
While any raster map layer can be used to represent the hue
information, map layers with a few very distinct colors
work best. Only raster map layers representing
continuously varying data like elevation, aspect, weights,
intensities, or amounts can suitably be used to provide
intensity and saturation information.
For example, a visually pleasing raster map layer can be
made by using a watershed map for the hue factor,
an aspect map for the intensity factor, and an
elevation map for saturation. (The user may wish
to leave out the elevation information for a first try.)
Ideally, the resulting image should resemble the view from
an aircraft looking at a terrain on a sunny day with a bit
of haze in the valleys.
THE PROCESS
Each map cell is processed individually. First, the working
color is set to the color of the corresponding cell in the
map layer chosen to represent HUE. Second, this
color is multiplied by the red intensity of that
cell in the INTENSITY map layer. This map layer
should have an appropriate gray-scale color table
associated with it. You can ensure this by using the color
manipulation capabilities of
d.display or
d.colors.
Finally, the color is made somewhat gray-based on the
red intensity of that cell in the
SATURATION map layer. Again, this map layer
should have a gray-scale color table associated with it.
NOTES
This program produces an image and (optionally) a raster
map layer with 1000 colors (10 intensities each of red,
green, and blue). The resulting image and raster map
layers will not display properly if the graphics display
monitor does not have at least 1000 colors while the user
is running in float colormode. Thus, unless the
display device has 1000 colors, it is necessary to run the
GRASS command:
-
d.colormode mode=fixed
before running d.his. Otherwise, the colors will be incorrectly
displayed on the graphics monitor.
Either (but not both) of the intensity or the saturation
map layers may be omitted. This means that it is possible
to produce output images that represent combinations of
his, hi, or hs.
SEE ALSO
d.3d
d.colormode
d.colors
d.colortable
d.display
hsv.rgb.sh
rgb.hsv.sh
parser
AUTHOR
James Westervelt, U.S. Army Construction Engineering Research Laboratory