An object of class "euclidean_path" created by euclideanPath().
zoom
Logical or Numeric. A numeric value >= 0 controls the degree of zoom. The default is 0.5.
unit.posts
Character. "distance" for mileposts; "time" for timeposts; NULL for no posts.
unit.interval
Numeric. Set interval between posts. When unit.posts is "distance", unit.interval automatically defaults to 50 meters. When unit.posts is "time", unit.interval automatically defaults to 60 seconds.