greenR (version 0.0.1.6)

chm_analysis: Robust ALS GEDI CHM Analysis and Visualization

Description

• Data Source: ALS GEDI v6 global canopy height model, Meta & WRI (2024).

• Interactive map is downsampled for browser performance; see max_cells_mapview.

Usage

chm_analysis(
  location = NULL,
  bbox = NULL,
  aoi_geojson = NULL,
  chm_tif = NULL,
  output_dir = "chm_output",
  apply_mask = TRUE,
  crop_result = TRUE,
  create_plots = TRUE,
  height_threshold = 2,
  max_tiles = 100,
  mapview_html = "chm_mapview.html",
  tmap_png = "chm_tmap.png",
  max_cells_mapview = 2e+05,
  n_cores = parallel::detectCores() - 1,
  chunk_size = 5,
  cache_tiles = TRUE,
  compression = "LZW",
  user_agent_string = "R/chm_analysis_script (your_email_or_project_url)",
  request_timeout = 300
)

Value

List with: raster, stats, static_map, mapview_file, plot_hist_file, tmap_file

Arguments

location

Character. Place name for AOI (e.g. "Basel, Switzerland").

bbox

Numeric. Bounding box (xmin, ymin, xmax, ymax, EPSG:4326).

aoi_geojson

Path to GeoJSON file defining AOI (overrides location/bbox).

chm_tif

Path to a local CHM raster (.tif). If supplied, skips tile download/mosaic.

output_dir

Output directory for all files.

apply_mask

Mask raster to AOI (default TRUE).

crop_result

Crop raster to AOI (default TRUE).

create_plots

Export static tmap and histogram (default TRUE).

height_threshold

Height (m) for tree coverage (default 2).

max_tiles

Max CHM tiles to use (default 100).

mapview_html

Output HTML file for interactive map.

tmap_png

Output PNG for publication-quality map.

max_cells_mapview

Maximum number of raster cells in the interactive map (default 1e5).

n_cores

Parallel cores for download (default: parallel::detectCores() - 1).

chunk_size

Tiles per parallel chunk (default 5).

cache_tiles

Cache tiles/AOI (default TRUE).

compression

Compression for output raster ("LZW", etc.).

user_agent_string

HTTP user agent string (for Nominatim, etc).

request_timeout

HTTP timeout in seconds (default 300).

Details

End-to-end or single-raster Canopy Height Model (CHM) analysis using Meta & WRI's 1m ALS GEDI v6 global dataset. Downloads, mosaics, crops, analyzes, and visualizes CHM data for any AOI, or analyzes a user-supplied .tif directly. Outputs both publication-quality (tmap) and interactive (mapview) maps, with progress/status reporting.

CRAN policy note: This function downloads data from the internet if location, bbox, or aoi_geojson are specified and the required local files are not present. Internet access is not permitted in CRAN checks or non-interactive sessions. If you are running in batch, automated, or non-interactive mode (including CRAN), you must provide all required files locally (e.g., chm_tif, aoi_geojson).

Examples

if (FALSE) {
# Example 1: AOI from bounding box (Zurich, Switzerland)
res_bbox <- chm_analysis(
  bbox = c(8.51, 47.36, 8.56, 47.40),
  output_dir = tempdir(), max_tiles = 2, create_plots = TRUE
)
print(res_bbox$stats)

# Example 2: AOI from location string (Parc La Grange, Geneva)
res_loc <- chm_analysis(
  location = "Parc La Grange, Geneva, Switzerland",
  output_dir = tempdir(), max_tiles = 2
)
print(res_loc$stats)

# Example 3: Analyze a user-supplied CHM raster
# Assume you have a file "my_canopy.tif" (projected or WGS84)
res_tif <- chm_analysis(
  chm_tif = "my_canopy.tif",
  output_dir = tempdir(),
  create_plots = TRUE,
  height_threshold = 3
)
print(res_tif$stats)
}