d.his(1)

1d.his(1)                      Grass User's Manual                     d.his(1)
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NAME

6       d.his   - Displays the result obtained by combining hue, intensity, and
7       saturation (his) values from user-specified input raster map layers.
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KEYWORDS

10       display
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SYNOPSIS

13       d.his
14       d.his help
15       d.his [-n] h_map=string  [i_map=string]   [s_map=string]
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17   Flags:
18       -n  Respect NULL values while drawing
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20   Parameters:
21       h_map=string
22           Name of layer to be used for HUE
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24       i_map=string
25           Name of layer to be used for INTENSITY
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27       s_map=string
28           Name of layer to be used for SATURATION
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DESCRIPTION

31       his stands for hue, intensity, and saturation.  This program produces a
32       raster  map  layer  providing  a  visually pleasing combination of hue,
33       intensity, and saturation  values  from  two  or  three  user-specified
34       raster map layers.
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36       The  human  brain  automatically  interprets  the vast amount of visual
37       information available according to basic rules.  Color, or hue, is used
38       to categorize objects.  Shading, or intensity, is interpreted as three-
39       dimensional texturing. Finally, the degree of haziness, or  saturation,
40       is  associated with distance or depth. This program allows data from up
41       to three raster map layers to be combined into an image  which  retains
42       the original information in terms of hue, intensity, and saturation.
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OPTIONS

45       This  program  can  be run non-interactively or interactively.  It will
46       run non-interactively if the user specifies on  the  command  line  the
47       name  of a map containing hue values (h_map), and the name(s) of map(s)
48       containing intensity values (i_map) and/or saturation  values  (s_map).
49       The  resulting  image  will be displayed in the active display frame on
50       the graphics monitor.
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52       Alternately, the user can run the program interactively by typing d.his
53       without naming parameter values on the command line.  In this case, the
54       program will prompt the user for parameter values  using  the  standard
55       GRASS parser interface.
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57       While  any  raster  map layer can be used to represent the hue informa‐
58       tion, map layers with a few  very  distinct  colors  work  best.   Only
59       raster  map  layers  representing continuously varying data like eleva‐
60       tion, aspect, weights, intensities, or amounts can suitably be used  to
61       provide intensity and saturation information.
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63       For example, a visually pleasing image can be made by using a watershed
64       map for the hue factor, an aspect map for the intensity factor, and  an
65       elevation map for saturation.  (The user may wish to leave out the ele‐
66       vation information for a first  try.)   Ideally,  the  resulting  image
67       should  resemble  the  view  from an aircraft looking at a terrain on a
68       sunny day with a bit of haze in the valleys.
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THE PROCESS

71       Each map cell is processed individually. First, the  working  color  is
72       set  to  the color of the corresponding cell in the map layer chosen to
73       represent HUE.  Second, this color is multiplied by the  red  intensity
74       of that cell in the INTENSITY map layer.  This map layer should have an
75       appropriate gray-scale color table associated with it. You  can  ensure
76       this by using the color manipulation capabilities of d.colors or r.col‐
77       ors.  Finally, the color is made somewhat gray-based on the red  inten‐
78       sity  of  that cell in the SATURATION map layer.  Again, this map layer
79       should have a gray-scale color table associated with it.
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NOTES

82       The name is misleading. The actual conversion used is
83         <U>H.i.s + <U>G.(1-s)
84       where
85         <U>H   is the R,G,B color from the hue map
86         i   is the red value from the intensity map
87         s   is the red value from the saturation map
88         <U>G   is 50% gray (R = G = B = 0.5)
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91       Either (but not both) of the intensity or the saturation map layers may
92       be  omitted.  This  means  that it is possible to produce output images
93       that represent combinations of his, hi, or hs.  Users wishing to  store
94       the  result  in  new  raster map layers instead of displaying it on the
95       monitor should use the program r.his.
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AUTHOR

102       James  Westervelt,  U.S. Army Construction Engineering Research Labora‐
103       tory
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105       Last changed: $Date: 2004/08/10 08:35:01 $
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107       Full index
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111GRASS 6.2.2                                                           d.his(1)