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Make a Relative Elevation Model (REM)

make_rem.Rd

This function creates a relative elevation model, or REM, based off an input digital elevation model (DEM) and the trajectory of a river. Simple inverse distance weighting is used to calculate "base" elevations at all pixels within the DEM, which are then subtracted to produce the output REM.

Usage

make_rem(
  dem,
  centerline = NULL,
  n_points = 1000,
  algorithm = "invdist:power=1",
  quiet = TRUE
)

Arguments

dem

Either a SpatRaster (created via terra::rast()) or an object that terra::rast() can read to create a SpatRaster.

centerline

Optionally, an sfc object (as created via sf::sfc()) representing the center of the target river to base the relative elevation model on. If NULL, the default, the longest river in the bounding box with a name in OpenStreetMap will be used instead.

n_points

The number of sample points along the river to base interpolation on. More points will make interpolation take longer.

algorithm

A string to control the interpolation algorithm. See the gdal_grid documentation at https://gdal.org/programs/gdal_grid.html for the available algorithms and customization options.

quiet

Boolean: should execution proceed "quietly", without messages (TRUE) or should progress updates be posted during centerline download and interpolation (FALSE)?

Value

A SpatRaster object (as created by terra::rast()), representing the difference between elevations in dem and the interpolated elevation

Examples

if (FALSE) { # rlang::is_interactive()
make_rem(system.file("elevation.tiff", package = "rrrem"))
}