Relating the world to the points of the compass
Display Figure 8.
Assume that the direction indicated by the blue axis in Figure 8 points toward the south.
Assume that the red axis points toward the west.
Then we can talk about directions in terms that most people understand.
The direction that is the opposite of the blue axis is north.
The direction that is the opposite of the red axis is east.
(The green axis is not part of this discussion because it points directly up toward the sky.)
Figure 8. The three axes belonging to the ground.