Skip to contents

Align and Standardize Raster Files to a Reference Raster

Source: R/raster_align.R
raster_align.Rd

Preprocessing function that aligns a batch of raster files to a specified reference raster by performing reprojection, resampling, and masking operations. Ensures all rasters share identical CRS, resolution, and spatial extent for later analyses.

Usage

raster_align(input_dir, output_dir, reference_raster,
             output_suffix = "_Masked_Updated", pattern = ".*\\.tif$",
             resample_method = "bilinear",
             overwrite = FALSE, verbose = TRUE)

Arguments

input_dir

Character. Directory containing the input raster files.

output_dir

Character. Directory where processed rasters will be saved.

reference_raster

Character, SpatRaster, or RasterLayer. File path or raster object used as the alignment reference.

output_suffix

Character. Suffix appended to output filenames. Default is "_Masked_Updated". Output files are named <original_name><output_suffix>.tif.

pattern

Character. Regular expression used to match raster files within input_dir. Default is ".*\.tif$".

resample_method

Character. Resampling method passed to resample. Default is "bilinear", which is appropriate for continuous variables. Use "near" for categorical rasters (e.g. land cover classes) to avoid interpolating between class codes. Other accepted values include "cubic" and "lanczos".

overwrite

Logical. If TRUE, overwrites existing output files. If FALSE (default), existing files are skipped.

verbose

Logical. If TRUE (default), prints progress messages during processing. Includes file counts, overwrite mode, per-file progress, and a completion summary.

Value

Invisibly returns a list containing:

  • output_files: Character vector of file paths written to output_dir.

  • n_processed: Integer. Number of rasters successfully processed in this call (excludes skipped files when overwrite = FALSE).

Details

For each raster in input_dir matching pattern, the function:

  1. Reprojects to the CRS of the reference raster

  2. Resamples to match the reference resolution using resample_method

  3. Masks values outside the reference raster's non-NA extent

  4. Saves the result as a GeoTIFF to output_dir

This preprocessing step ensures spatial alignment before applying other downstream analyses such as temporally_explicit_extraction or scale_rasters.

See also

Preprocessing: scale_rasters, temporally_explicit_extraction

Examples

raw_dir <- system.file("extdata/rasters_raw", package = "TemporalModelR")

ref     <- file.path(raw_dir, "elevation.tif")

out_dir <- file.path(tempdir(), "aligned")

raster_align(
  input_dir        = raw_dir,
  output_dir       = out_dir,
  reference_raster = ref,
  overwrite        = TRUE,
  verbose          = FALSE
)