Weighted geodesic tessellation (core)

Computes a weighted tessellation using domain-constrained (geodesic) distances. Distances are calculated as shortest-path distances through a rasterised domain mask.

Usage

weighted_voronoi_geodesic(
  points_sf,
  weight_col,
  boundary_sf,
  res = 20,
  weight_transform = function(w) w,
  weight_model = c("multiplicative", "power", "additive"),
  weight_power = 1,
  close_mask = TRUE,
  close_iters = 1,
  resistance_rast = NULL,
  dem_rast = NULL,
  use_tobler = TRUE,
  tobler_v0_kmh = 6,
  tobler_a = 3.5,
  tobler_b = 0.05,
  min_speed_kmh = 0.25,
  anisotropy = c("none", "terrain"),
  uphill_factor = 1,
  downhill_factor = 1,
  island_min_cells = 5,
  island_fill_iter = 50,
  geodesic_engine = c("classic", "multisource"),
  return_polygons = TRUE,
  prepared = NULL,
  verbose = TRUE
)

Arguments

points_sf

An sf POINT object containing generator locations and attributes.

weight_col

Character. Name of the weight column in points_sf.

boundary_sf

An sf POLYGON/MULTIPOLYGON defining the domain.

res

Numeric. Raster resolution in CRS units (e.g. metres).

weight_transform

Function. Transforms weights before allocation. Must return finite, strictly positive values.

weight_model

Character. One of "multiplicative", "power", or "additive". Controls how distances and weights combine into effective cost.

weight_power

Numeric > 0. Only used when weight_model = "power". Controls the distance exponent.

close_mask

Logical. If TRUE, applies a morphological closing to the raster mask (geodesic only).

close_iters

Integer. Number of closing iterations (geodesic only).

resistance_rast

Optional SpatRaster giving movement resistance (>0). Overrides dem_rast/Tobler when provided.

dem_rast

Optional SpatRaster providing elevation or resistance surface. Must align with the tessellation domain and resolution.

use_tobler

Logical; if TRUE, apply Tobler's hiking function to convert slope into isotropic movement cost.

tobler_v0_kmh

Base walking speed on flat terrain (km/h).

tobler_a

Tobler exponential slope coefficient (default -3.5).

tobler_b

Tobler slope multiplier (default 0.05).

min_speed_kmh

Minimum allowed speed to avoid infinite costs.

anisotropy

Character. Directional cost model for geodesic distance.

"none"

Standard isotropic geodesic distance (default).

"terrain"

Direction-dependent movement based on terrain slope (DEM required).

uphill_factor

Numeric > 0. Multiplier controlling additional cost of uphill movement when anisotropy = "terrain". Values > 1 penalise uphill movement more strongly.

downhill_factor

Numeric > 0. Multiplier controlling ease of downhill movement when anisotropy = "terrain". Values > 1 make downhill travel easier.

island_min_cells

Integer. Minimum patch size used in island removal.

island_fill_iter

Integer. Maximum iterations for filling reassigned cells.

geodesic_engine

Character. Geodesic allocation engine; one of "classic" or "multisource".

return_polygons

Logical. If TRUE, polygonise the cleaned allocation raster and attach point attributes. If FALSE, return allocation outputs only.

prepared

Optional prepared geodesic context created by prepare_geodesic_context() for repeated compatible geodesic runs.

verbose

Logical. If TRUE, prints progress.

Value

A list containing polygon output, allocation raster, and weights.