barrier_sf: An sf object with polygons defining the barriers. For example, a coastline dataset for ocean data. Note that this object must have the same projection as the data used togenerate the x and y columns in ‘spde_obj’.
range_fraction: The fraction of the spatial range that barrier triangles have.
proj_scaling: If spde_obj was created with scaling of the coordinates after the projection (e.g., dividing UTMs by 1000 so the spatial range is on a reasonable scale) the x and y values in spde_obj are multiplied by this scaling factor before applying the projection from barrier_sf.