1r.shaded.relief(1) Grass User's Manual r.shaded.relief(1)
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6 r.shaded.relief - Creates shaded relief map from an elevation map
7 (DEM).
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10 raster, elevation
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13 r.shaded.relief
14 r.shaded.relief help
15 r.shaded.relief map=string [shadedmap=string] [altitude=integer]
16 [azimuth=integer] [zmult=float] [scale=float] [units=string]
17 [--overwrite] [--verbose] [--quiet]
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19 Flags:
20 --overwrite
21 Allow output files to overwrite existing files
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23 --verbose
24 Verbose module output
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26 --quiet
27 Quiet module output
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29 Parameters:
30 map=string
31 Input elevation map
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33 shadedmap=string
34 Output shaded relief map name
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36 altitude=integer
37 Altitude of the sun in degrees above the horizon
38 Options: 0-90
39 Default: 30
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41 azimuth=integer
42 Azimuth of the sun in degrees to the east of north
43 Options: 0-360
44 Default: 270
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46 zmult=float
47 Factor for exaggerating relief
48 Default: 1
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50 scale=float
51 Scale factor for converting horizontal units to elevation units
52 Default: 1
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54 units=string
55 Set scaling factor (applies to lat./long. locations only)
56 Options: meters,feet
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59 r.shaded.relief is a Bourne shell script that creates a raster shaded
60 relief map based on current resolution settings and on sun altitude,
61 azimuth, and z-exaggeration values entered by the user. If no output
62 shademap name is given, the new shaded relief map is named .shade. The
63 map is assigned a grey-scale color table.
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65 If no parameters are provided on startup, this program is interactive;
66 thus if the user enters the command: r.shaded.relief
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68 The program then prompts the user to enter values for: The altitude of
69 the sun in degrees above the horizon (a value between 0 and 90
70 degrees), and The azimuth of the sun in degrees to the east of north (a
71 value between 0 and 360 degrees). The name of a raster map layer to
72 provide elevation values for the shaded relief map. Typically, this
73 would be a map layer of elevation; however, any raster map layer can be
74 named. The scaling parameter, which compensates for a different hori‐
75 zontal scale than vertical scale. If 'scale' is a number then the ewres
76 and nsres are multiplied by that scale to calculate the shading.
77 (Default=1.0 for equivalent horizontal and vertical scales.)
78 For ETOPO2 data a scale factor of 10000 generates an acceptable shading
79 effect. For the special case when a latitude-longitude projection is
80 used with an elevation map measured in meters or feet, the units can be
81 set to automatically set the horizontal scale to the the number of
82 meters or feet in a degree of latitude. The script scales latitude and
83 longitude equally, so it's only approximately right, but for shading
84 it's close enough. It makes the difference between a usable and unus‐
85 able shade. The zmult exaggeration factor that changes the apparent
86 relief for the shaded relief map. This can be any positive (or nega‐
87 tive) floating point value. (Default=1.0)
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89 Specifically, r.shaded.relief executes a r.mapcalc statement. Refer to
90 the manual entry for r.mapcalc for an explanation of the filtering syn‐
91 tax shown in the above expression. See, for example, the section on
92 "The Neighborhood Modifier".
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94 r.shaded.relief then runs r.colors to assign a grey-scale color table
95 to the new shaded relief map.
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98 To visually improve the result of shade maps from low resolution eleva‐
99 tion models, use r.resamp.interp with bilinear or bicubic method to
100 resample the DEM at higher resolution. r.shaded.relief is then run on
101 the resampled DEM.
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104 This program is simply a shell script. Users are encouraged to make
105 their own shell scripts using similar techniques. See $GIS‐
106 BASE/scripts/r.shaded.relief.
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109 An Algebra for GIS and Image Processing, by Michael Shapiro and Jim
110 Westervelt, U.S. Army Construction Engineering Research Laboratory
111 (March/1991) (get from GRASS web site).
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113 d.his,
114 g.region,
115 r.blend,
116 r.colors,
117 r.mapcalc,
118 r.resamp.interp
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121 Jim Westervelt, U.S. Army Construction Engineering Research Laboratory
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123 Last changed: $Date: 2008-03-26 15:02:09 +0100 (Wed, 26 Mar 2008) $
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125 Full index
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127 © 2003-2008 GRASS Development Team
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131GRASS 6.3.0 r.shaded.relief(1)