Calculate the shortest path through a visibility network between two points

Given a segs_tbl tibble created by get_barrier_segments() and a vis_graph created by prt_visgraph(), this function adds a geometry column to segs_tbl that is the shortest path from the POINT geometries provided in the start_pt / end_pt columns of segs_tbl.

Usage

prt_shortpath(segs_tbl, vis_graph, blend = TRUE)

Arguments

segs_tbl: tibble from get_barrier_segments()
vis_graph: sfnetwork from prt_visgraph()
blend: boolean whether to blend start/end points into network

Value

segs_tbl data frame with added geometry column for shortest path LINESTRING that connects the start_pt and end_pt coordinates

Details

The blend = TRUE argument will blend all of the start_pt / end_pt geometries in segs_tbl into the vis_graph network via the sfnetworks::st_network_blend() function. This process creates new nodes within vis_graph that are positioned at the perpendicular intersection between each point and the nearest edge. With blend = FALSE the nearest existing node is used. In highly complex coastlines, the use of blend = FALSE could result in re-routed paths that still intersect land or do not accurately represent the intended result. For less complex situations and when computational speed is important, blend = FALSE may be appropriate.

This function is typically called directly by prt_reroute and users are discouraged from using this function directly.