Usage
gdaldem(mode, input_dem, output, of, compute_edges, alg, b, co, q, z, s, az,
alt, combined, p, trigonometric, zero_for_flat, color_text_file, alpha,
exact_color_entry, nearest_color_entry, additional_commands,
output_Raster = FALSE, verbose = FALSE)
Arguments
mode
Character.
("hillshade"|"slope"|"aspect"|"color-relief"|"TRI"|"TPI"|"roughness")
input_dem
Character. The input DEM raster to be
processed.
output
Character. The output raster produced.
of
Character. Select the output format. The
default is GeoTIFF (GTiff). Use the short format name.
compute_edges
Logical. (GDAL >= 1.8.0) Do the
computation at raster edges and near nodata values.
alg
Character. "ZevenbergenThorne" (GDAL >= 1.8.0)
Use Zevenbergen & Thorne formula, instead of Horn's
formula, to compute slope & aspect. The litterature
suggests Zevenbergen & Thorne to be more suited to smooth
landscapes, whereas Horn's formula to
b
Numeric. Select an input band to be processed.
Bands are numbered from 1.
co
Character. (GDAL >= 1.8.0) Passes a creation
option ("NAME=VALUE") to the output format driver.
Multiple -co options may be listed. See format specific
documentation for legal creation options for each
format.
q
Logical. Suppress progress monitor and other
non-error output.
z
Numeric. (mode=="hillshade") vertical
exaggeration used to pre-multiply the elevations.
s
Numeric. (mode=="hillshade" | mode=="slope)
ratio of vertical units to horizontal. If the horizontal
unit of the source DEM is degrees (e.g Lat/Long WGS84
projection), you can use scale=111120 if the vertical
units are meters (or scale=370400 if t
az
Numeric. (mode=="hillshade") azimuth of the
light, in degrees. 0 if it comes from the top of the
raster, 90 from the east, ... The default value, 315,
should rarely be changed as it is the value generally
used to generate shaded maps.
alt
Numeric. (mode=="hillshade") altitude of the
light, in degrees. 90 if the light comes from above the
DEM, 0 if it is raking light.
combined
Character. (mode=="hillshade") "combined
shading" (starting with GDAL 1.10) a combination of slope
and oblique shading.
p
Logical. (mode=="slope") if specified, the slope
will be expressed as percent slope. Otherwise, it is
expressed as degrees.
trigonometric
Logical. (mode=="aspect") return
trigonometric angle instead of azimuth. Thus 0deg means
East, 90deg North, 180deg West, 270deg South.
zero_for_flat
Logical. (mode=="aspect") By using
those 2 options, the aspect returned by gdaldem aspect
should be identical to the one of GRASS r.slope.aspect.
Otherwise, it's identical to the one of Matthew Perry's
aspect.cpp utility.
color_text_file
Character. (mode=="color-relief")
text-based color configuration file (see Description).
alpha
Logical. (mode=="color-relief") add an alpha
channel to the output raster.
exact_color_entry
Logical. (mode=="color-relief")
use strict matching when searching in the color
configuration file. If none matching color entry is
found, the "0,0,0,0" RGBA quadruplet will be used.
nearest_color_entry
Logical.
(mode=="color-relief") use the RGBA quadruplet
corresponding to the closest entry in the color
configuration file.
additional_commands
Character. Additional commands
to pass directly to gdalsrsinfo.
output_Raster
Logical. Return output dst_dataset
as a RasterBrick?