Interpolate elevations from points along a centerline

Usage

calc_centerline_interpolation(
  points_on_line,
  dem,
  algorithm = "invdist:power=1",
  gdal_options = NULL,
  quiet = TRUE
)

Arguments

points_on_line: The output from points_along_line(): an sfc object of points along the centerline, which will be used as data points for interpolation.
dem: Either a SpatRaster (created via terra::rast()) or an object that terra::rast() can read to create a SpatRaster.
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.
gdal_options: Optionally, a vector of options to pass to gdal_grid via sf::gdal_utils(). See the full list of options online at https://gdal.org/programs/gdal_grid.html. See Details.
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 outputs of the interpolation process.

Details

The bulk of the processing time for this function involves calling gdal_grid via sf::gdal_utils(). The results from this function call are then written out as a TIFF file before being read back into the R session.

You can choose to pass options to gdal_grid. However, passing any of -a, -txe, -tye, -tr, -outsize, and zfield will cause an error. Possible options to speed up processing include passing c("-co", "NUM_THREADS=ALL_CPUS") in order to write the TIFF using multiple threads, or c("--config" "GDAL_CACHEMAX", "30%") (or another value) to increase cache utilization above the default 5%.

Examples

if (FALSE) { # rlang::is_interactive()
dem <- system.file("elevation.tiff", package = "rrrem")
centerline <- get_river_centerline(dem)
center_points <- points_along_line(centerline, n_points = n_points)
interpolated_raster <- calc_centerline_interpolation(
  center_points,
  dem,
  quiet = quiet
)
}