Raster Meets Point Data - Open Source Geospatial Tools: Applications in Earth Observation - page 153

input_dem
The input DEM raster to be processed.
output_xxx_map
The output raster produced.
-of format
Select the output format. The default is GeoTIFF (GTiff). Use the short format
name.
-compute_edges
(from GDAL 1.8.0) Do the computation at raster edges and near no-data values.
-alg ZevenbergenThorne
(from GDAL 1.8.0) Use Zevenbergen and Thorne formula, instead of Horn's
formula, to compute slope and aspect. The literature suggests Zevenbergen and
Thorne to be more suited to smooth landscapes, whereas Horn's formula to
perform better on rougher terrain.
-b band
Select an input band to be processed. Bands are numbered from 1.
-co "NAME=VALUE"
Passes a creation option to the output format driver. Multiple -co options may
be listed. See format specific documentation for legal creation options for each
format.
-q
Suppress progress monitor and other non-error output.
10.6.1 Hillshade
The hillshade is a visualization mode for simulating a shaded relief effect, based
on a light source at a specified azimuth and zenith angle (referred to as altitude ).
Both the horizontal and vertical units in the input DEM can be scaled independently.
The output data type is an 8-bit character (Byte), with values from 0 to 255 with a
no-data value fixed to 0.
-z zFactor
vertical exaggeration used to pre-multiply the elevations.
-s scale
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 in feet).
-az azimuth
azimuth of the light, in degrees. 0 if it comes from the top of the raster, 90 from
the east, etc. The default value, 315, should rarely be changed as it is the value
generally used to generate shaded maps.