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Rasterize range polygons onto the global 0.05° cell grid (whole range)

Source: R/ingest.R
cells_from_ranges.Rd

Turns presence polygons (an IUCN/BOTW/NMFS range, a critical-habitat polygon) into (cell_id, value) on the v8 grid, capturing the whole distribution — land AND ocean (v8 does not mask land). Uses exactextractr, which is fast and robust to messy geometry (self-intersections, MULTISURFACE — the usual range-map "funk"). By default every cell the polygon overlaps gets value (100 = presence); cover = TRUE weights by the fraction of each cell covered. Marine share is separate — see cells_pct_marine().

Usage

cells_from_ranges(
  x,
  cellid_tif,
  value = 100,
  cover = FALSE,
  min_coverage = 0,
  max_vertices = 1000,
  exact = FALSE
)

Arguments

x

an sf/SpatVector of (multi)polygons in EPSG:4326 -180,180

cellid_tif

path to the GLOBAL cell-id COG (cell_id for every cell)

value

value for a covered cell. For range datasets this is the species' extinction-risk score from compute_er_score() (e.g. compute_er_score("NMFS:EN") = 100, "NMFS:TN" = 50, "IUCN:CR" = 50) — NEVER a hard-coded number. Default 100 is only a convenience.

cover

logical; TRUE = coverage fraction × value, FALSE (default) = flat value for any overlap

min_coverage

keep cells whose covered fraction exceeds this (default 0 = any overlap; use 0.5 for a majority/centre-like rule)

max_vertices

(exact path only) subdivide the range into chunks of at most this many vertices before rasterizing (default 1000). A globe-spanning range (a wide-ranging seabird) is one massive multipolygon that hangs st_union / exact_extract; subdividing bounds each chunk's raster window so it never touches the whole-globe polygon. Cells are de-duplicated afterward, so chunking is equivalent to a union here. Needs the lwgeom package; without it, falls back to the single-union path.

exact

force the coverage-aware exact_extract path even for the flat any-overlap case (default FALSE). By default the flat case (cover=FALSE, min_coverage=0) uses the ~2x-faster terra::rasterize touches path, which yields an identical cell set; set TRUE for the boundary-exact coverage>0 behavior. cover=TRUE or min_coverage>0 always use the exact path.

Value

a tibble (cell_id integer, val double); empty if no overlap

Examples

if (FALSE) { # \dontrun{
r <- msens::cells_from_ranges(ply_sp, cellid_tif)               # presence = 100, whole range
r <- msens::cells_from_ranges(ply_sp, cellid_tif, cover = TRUE) # coverage-weighted
} # }