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Prepare a hazard zone from an inundation raster

Source: R/prepare.R
prepare_hazard_zone.Rd

Converts an inundation raster to a binary hazard-zone raster or polygon using a threshold. This is intentionally general so users can adapt it to tsunami, flood, storm-surge, or other hazard layers.

Usage

prepare_hazard_zone(
  inundation,
  threshold = 0,
  land_mask = NULL,
  target_crs = NULL,
  as_polygon = TRUE,
  dissolve = TRUE
)

Arguments

inundation

A SpatRaster or path to a raster.

threshold

Numeric threshold. Cells greater than threshold are treated as inside the hazard zone.

land_mask

Optional SpatRaster or SpatVector used to mask the hazard zone to land.

target_crs

Optional output CRS. Use a projected CRS in meters for later distance calculations.

as_polygon

Logical. If TRUE, return a polygon hazard zone.

dissolve

Logical. If TRUE, dissolve polygon pieces.

Value

A binary SpatRaster or polygon SpatVector.

Examples

r <- terra::rast(nrows = 5, ncols = 5, xmin = 0, xmax = 5, ymin = 0, ymax = 5)
terra::values(r) <- c(rep(0, 12), rep(1, 13))
zone <- prepare_hazard_zone(r, threshold = 0, as_polygon = TRUE)
zone
#> class       : SpatVector
#> geometry    : polygons
#> dimensions  : 1, 0  (geometries, attributes)
#> extent      : 0, 5, 0, 3  (xmin, xmax, ymin, ymax)
#> coord. ref. : lon/lat WGS 84 (CRS84) (OGC:CRS84)