r.shaded.relief(1)

1r.shaded.relief(1)            Grass User's Manual           r.shaded.relief(1)
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NAME

6       r.shaded.relief   -  Creates  shaded  relief  map from an elevation map
7       (DEM).
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KEYWORDS

10       raster, elevation
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SYNOPSIS

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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DESCRIPTION

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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NOTES

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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FILES

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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AUTHOR

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)