Well, based on the film, we've seen that when you enter the meditation chamber, the pod is directly in front of you, but the ramp does not face the doorway. If the doorway is on the Eastern wall, then the access ramp to Vader's pod faces the south. That's why Piett walks around the pod to talk to Vader. When Vader uses the viewscreen to strangle Ozzle, he spins his chair 180 degrees, placing the viewscreen on the north wall. The area where the Emperor's hologram appears can only be south of the pod.