[To show both plan and animation, the two movies have been reduced with a factor 5.]

Preview: Traversing the Axis of Action (180 Degrees Rule)
As long as it is an isolated shot, the direction of an object’s movement is of little importance. However, if we glue several shots together it can cause problems. In Movement version 3, the camera stays 5 seconds at the bottom of the ground map. This is the first shot. Then we move the camera to the top and rotate 180 degrees. This is the second shot. For the objective viewer the result is very confusing. In the same act, the actor walks both from left to right and vice versa. The illusion of a continuous act is disrupted.
This phenomenon is called "traversing the axis of action". The axis is an imaginary line that indicates the direction of movement (or the gaze direction of the eyes). If traversing the axis leads to disorientation it is considered as an infringement of the '180 degree rule'.
In Movement version 4 the camera is at the bottom of the map. The man walks from left to right. During the take the camera is moving over the axis to the top, continuously keeping the character in the picture. Now it is clear to the viewer that the direction is reversed.