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rsaga.hillshade.Rd
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rsaga.hillshade.Rd
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% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/RSAGA-modules.R
\name{rsaga.hillshade}
\alias{rsaga.hillshade}
\title{Analytical hillshading
Analytical hillshading calculation.}
\usage{
rsaga.hillshade(
in.dem,
out.grid,
method = "standard",
azimuth = 315,
declination = 45,
exaggeration = 4,
...
)
}
\arguments{
\item{in.dem}{Input digital elevation model (DEM) as SAGA grid file (default extension: \code{.sgrd}).}
\item{out.grid}{Output hillshading grid (SAGA grid file). Existing files will be overwritten!}
\item{method}{Available choices (character or numeric): \code{"standard"} (or \code{0} - default), \code{"max90deg.standard"} (\code{1}), \code{"combined.shading"} (\code{2}), \code{"ray.tracing"} (\code{3}). See Details.}
\item{azimuth}{Direction of the light source, measured in degree clockwise from the north direction; default 315, i.e. northwest.}
\item{declination}{Declination of the light source, measured in degree above the horizon (default 45).}
\item{exaggeration}{Vertical exaggeration of elevation (default: 4). The terrain exaggeration factor allows to increase the shading contrasts in flat areas.}
\item{...}{Optional arguments to be passed to \code{\link[=rsaga.geoprocessor]{rsaga.geoprocessor()}}, including the \code{env} RSAGA geoprocessing environment.}
}
\value{
The type of object returned depends on the \code{intern} argument passed to the \code{\link[=rsaga.geoprocessor]{rsaga.geoprocessor()}}. For \code{intern=FALSE} it is a numerical error code (0: success), or otherwise (default) a character vector with the module's console output.
}
\description{
Analytical hillshading
Analytical hillshading calculation.
}
\details{
The Analytical Hillshading algorithm is based on the angle between the surface and the incoming light beams, measured in radians.
}
\note{
While the default azimuth of 315 degree (northwest) is not physically meaningful on the northern hemisphere, a northwesterly light source is required to properly depict relief in hillshading images. Physically correct southerly light sources results a hillshade that would be considered by most people as inverted: hills look like depressions, mountain chains like troughs.
}
\examples{
\dontrun{rsaga.hillshade("dem.sgrd","hillshade")}
}
\seealso{
\code{\link[=rsaga.solar.radiation]{rsaga.solar.radiation()}}, \code{\link[=rsaga.insolation]{rsaga.insolation()}}
}
\author{
Alexander Brenning (R interface), Olaf Conrad (SAGA module)
}
\keyword{interface}
\keyword{spatial}