Interpolate a distance surface from least-cost distance points — interpolate_distance

Uses thin-plate spline interpolation to create a continuous distance surface. This preserves the original paper-script approach while keeping interpolation optional. For most package workflows, make_evac_polygons() is the simpler output.

Usage

interpolate_distance_surface(
  distance_points,
  region_area,
  study_area,
  resolution_coarse = 100,
  resolution_fine = 1,
  distance_col = "distance"
)

Arguments

distance_points: Point layer with a distance column.
region_area: Broader analysis region used for interpolation extent.
study_area: Final study area used to crop and mask the output.
resolution_coarse: Coarse interpolation resolution.
resolution_fine: Fine output resolution.
distance_col: Name of distance column in distance_points.

Value

A SpatRaster distance surface.

Examples

if (requireNamespace("fields", quietly = TRUE)) {
  pts <- terra::vect(
    data.frame(
      x = c(0, 1, 0, 1, 0.5, 1.5),
      y = c(0, 0, 1, 1, 0.5, 1.5),
      distance = c(0, 5, 10, 15, 7, 20)
    ),
    geom = c("x", "y"),
    crs = "EPSG:3857"
  )
  area <- terra::as.polygons(terra::rast(nrows = 2, ncols = 2, xmin = -1, xmax = 2,
    ymin = -1, ymax = 2, vals = 1, crs = "EPSG:3857"), dissolve = TRUE)
  interpolate_distance_surface(pts, area, area, resolution_coarse = 0.5, resolution_fine = 1)
}
#> class       : SpatRaster
#> size        : 3, 3, 1  (nrow, ncol, nlyr)
#> resolution  : 1, 1  (x, y)
#> extent      : -1, 2, -1, 2  (xmin, xmax, ymin, ymax)
#> coord. ref. : WGS 84 / Pseudo-Mercator (EPSG:3857)
#> source(s)   : memory
#> name        :      last
#> min value   :  0.331864
#> max value   : 20.422298