gdaldem {gdalUtilities}

Interface to GDAL's gdaldem utility

Description

This function provides an interface mirroring that of the GDAL command-line app gdaldem. For a description of the utility and the arguments that it takes, see the documentation at https://gdal.org/programs/gdaldem.html.

Usage

gdaldem(
  mode,
  input_dem,
  output_map,
  ...,
  of,
  compute_edges,
  alg,
  b,
  co,
  q,
  z,
  s,
  az,
  alt,
  combined,
  multidirectional,
  igor,
  p,
  trigonometric,
  zero_for_flat,
  color_text_file = character(0),
  alpha,
  exact_color_entry,
  nearest_color_entry,
  config_options = character(0),
  dryrun = FALSE
)

Arguments

mode

Character, one of "hillshade", "slope", "color-relief", "TRI", "TPI", "roughness", indicating which of the available processing modes is to be used.

input_dem

Path to a GDAL-supported readable DEM datasource.

output_map

Character. Path to a GDAL-supported output file.

...

Here, a placeholder argument that forces users to supply exact names of all subsequent formal arguments.

of, compute_edges, alg, b, co, q, z, s, az, alt, combined

See the GDAL project's gdaldem documentation for details.

multidirectional, igor, p, trigonometric, zero_for_flat

See the GDAL project's gdaldem documentation for details.

color_text_file, alpha, exact_color_entry, nearest_color_entry

See the GDAL project's gdaldem documentation for details.

config_options

A named character vector with GDAL config options, of the form c(option1=value1, option2=value2). (See here for a complete list of supported config options.)

dryrun

Logical (default FALSE). If TRUE, instead of executing the requested call to GDAL, the function will print the command-line call that would produce the equivalent output.

Value

Silently returns path to output_map.

Author(s)

Joshua O'Brien

Examples

## Prepare file paths
td <- tempdir()
in_dem <- system.file("extdata/maunga.tif", package = "gdalUtilities")
out_slope  <- file.path(td, "slope.tif")
out_shade  <- file.path(td, "shade.tif")
out_aspect <- file.path(td, "aspect.tif")

## Apply DEM processing
gdaldem("slope", in_dem, out_slope)
gdaldem("shade", in_dem, out_shade)
gdaldem("aspect", in_dem, out_aspect)

## View results
if(require(terra)) {
    op <- par(mfcol = c(1, 2))
    plot(rast(in_dem),     main = "elevation")
    plot(rast(out_slope),  main = "slope")
    plot(rast(out_shade),  main = "hillshade")
    plot(rast(out_aspect), main = "aspect")
    par(op) ## Reset parameters to preexisting values
}