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, output_Raster = FALSE,
ignore.full_scan = TRUE, 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 perform
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 they are
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.
output_Raster
Logical. Return output dst_dataset as a RasterBrick?
ignore.full_scan
Logical. If FALSE, perform a brute-force scan if other installs are not found. Default is TRUE.
verbose
Logical. Enable verbose execution? Default is FALSE.