Calculate distance restricted by obstructions

Usage

calc_dist_restricted(
  mymap,
  obspolys = NULL,
  targetcoords,
  FlightGridcorrection_3035,
  directions = 16,
  obspenalty = 1e+08,
  maxdist = 9000
)

Arguments

mymap: A raster in which grid cells on land are assumed to have missing (NA) values
obspolys: Polygons associated with obstacles; if NULL there are assumed to be no obstacles other than land
FlightGridcorrection_3035: The 'flight correction' layer required by gdistance to correct for latitude (see gdistance)
obspenalty: Penalty value associated with crossing an obstruction; a positive number
maxdist: Maximum distance, in km; above this value are fixed to zero

Value

Raster, containing distance to target from each grid, avoiding obstructions, in kilometres

Details

Grid cells are treated as obstructed if (a) they have a missing (NA) value in the map, or, if "obspolys" has been provided, the grid cell lies within any of the polygons in "obspolys". Created 26 May 2024 based on "make_fltdist_scen" in SeabORD, but (a) for a single colony and (b) for obstruction either by land or other (e.g. footprints)