I always tell my students...(my field has a big hill south and west,Tress North and east) that if you keep your aircraft above the tress by sight you won't hit them. if you have to descend at the tress or the south hill like we do its just a matter of depth percepition...which is a function of both eyes...make sure to get your head cranked around so that both eyes can see the airplane well.....
Good flyin to ya