Have never taught otherwise than to base circuit position w.r.t. the runway. Even when I taught at a very large airline & military cadet school (who shall be nameless but were Bloody Awesomely Expensive) who insisted on circuits w.r.t. geographical points it's possible to rephrase things sensibly eg "...turn base at 45 deg from the threshold at the correct spacing and you will find yourself over xxx object. Note that the object only gives an indication of your position error. It's not a target to fly towards..." etc