Download and Process a GEE Raster Layer into a Cloud-Optimized GeoTIFF

Generic function for downloading any raster data from Google Earth Engine. Handles authentication, export management, file downloading, and processing into a local Cloud-Optimized GeoTIFF. Exports to Google Drive root to avoid GEE folder duplication bugs.

Uso

download_gee_layer(
  boundary_layer,
  iso3,
  gee_project,
  asset_id,
  file_prefix,
  output_dir = here::here(),
  scale = 10,
  datatype = "INT1U",
  googledrive_folder = NULL,
  wait_time = 5,
  band = NULL,
  composite_method = c("mosaic", "mode", "median", "mean"),
  year_override = NULL,
  pus = NULL,
  aggregate_to_pus = FALSE,
  aggregation_reducer = c("mode", "mean", "sum")
)

Argumentos

boundary_layer: An sf object defining the spatial boundary of interest.
iso3: Character. Three-letter ISO country code for filename generation.
gee_project: Character. Google Earth Engine cloud project ID. This is required and must be a valid GEE project you have access to. Find your project ID in the GEE Code Editor.
asset_id: Character. Earth Engine ImageCollection asset ID (e.g., "projects/sat-io/open-datasets/...").
file_prefix: Character. Prefix for export filename and GEE task description.
output_dir: Character. Path to directory for saving the final raster file. Defaults to project root via here::here().
scale: Numeric. Resolution of the exported image in meters. Default is 10. Ignored when aggregate_to_pus = TRUE (uses PU resolution instead).
datatype: Character. Output datatype (GDAL style), e.g., "INT1U" or "FLT4S". Default is "INT1U".
googledrive_folder: Character or NULL. Google Drive folder name for exports. Currently defaults to NULL (Drive root) to avoid a GEE folder duplication bug.
wait_time: Numeric. Maximum time in minutes to wait for the GEE export to appear in Google Drive. Default is 5. Increase for large exports.
band: Character or NULL. Specific band to select from the image. If NULL, uses all bands. Useful for datasets like Dynamic World ("label") or ESA WorldCover ("Map").
composite_method: Character. Method for creating temporal composite: "mosaic" (default), "mode" (most frequent value), "median", or "mean". Use "mode" for categorical data like Dynamic World.
year_override: Numeric or NULL. If provided, use this year instead of automatically detecting the most recent year with data.
pus: SpatRaster or NULL. Planning units raster for GEE-side aggregation. When provided with aggregate_to_pus = TRUE, the export will be resampled to match the PU resolution and projection in GEE before download.
aggregate_to_pus: Logical. If TRUE and pus is provided, aggregate the data to planning unit resolution in GEE before export. This significantly speeds up processing by eliminating local resampling. Default is FALSE.
aggregation_reducer: Character. Reducer to use for GEE-side aggregation: "mode" (default, for categorical data), "mean", or "sum".

Valor

A SpatRaster object written to disk, or NULL if export timed out. When aggregate_to_pus = TRUE, the result has attribute pre_aggregated = TRUE.

Detalles

For most use cases, prefer the higher-level wrapper functions like download_esri_lulc_data() or download_global_pasture_data() which have sensible defaults for common datasets.

Ver también

download_esri_lulc_data(), download_global_pasture_data(), download_lulc_data()

Ejemplos

if (FALSE) { # \dontrun{
# Download ESRI LULC data for Ghana
lulc <- download_gee_layer(
  boundary_layer = ghana_boundary,
  iso3 = "GHA",
  gee_project = "my-gee-project",
  asset_id = "projects/sat-io/open-datasets/landcover/ESRI_Global-LULC_10m_TS",
  file_prefix = "esri_10m_lulc",
  scale = 10,
  datatype = "INT1U"
)

# Download with GEE-side aggregation to planning units
lulc_agg <- download_gee_layer(
  boundary_layer = ghana_boundary,
  iso3 = "GHA",
  gee_project = "my-gee-project",
  asset_id = "projects/sat-io/open-datasets/landcover/ESRI_Global-LULC_10m_TS",
  file_prefix = "esri_10m_lulc_agg",
  pus = planning_units,
  aggregate_to_pus = TRUE,
  aggregation_reducer = "mode"
)
} # }