From: The World In Your Head by Steven Lehar

Fig. 10.8 (A) For navigation beyond the range of immediately perceived space, a mental map appears in a disconnected mental space, in a manner somewhat like the experience of consulting an actual map. Usually the mental map appears with the forward direction uppermost. (B) This mental map can be rotated and scaled mentally, and it can even be scaled up to full size and superimposed on the perceived world, with the proper perspective distortions automatically applied.