The "upside-down" problem

Everyone who purchases 3D glasses should be rewarded with a spectacular experience, especially when using a big projector screen! But parallax inversion often occurs when 3D glasses are first installed, especially when using a projector screen. It is heartbreaking to think that many virtual reality fans could be putting their 3D glasses back in the box not realizing that their disappointment is due to a problem that is easily fixable.

Some disappointed users may discover that the otherwise horrible looking video looks great, but only if they wear the 3D glasses upside down! A sure sign of parallax inversion.

HOW TO FIX PARALLAX INVERSION

 

More: Troubled Focus

Parallax inversion is especially confusing because your system seems to be creating depth perception. At first there is an exciting taste of 3D but your eyes have great trouble switching from one depth to another. You will find yourself making endless adjustments to the stereo convergence settings, but the problem only improves by turning the stereo-depth down to near zero! Continued viewing most often causes nothing but frustration and severe eyestrain.

Definition

In 3D stereo imaging parallax is the separation between the right-eye image of an object and the left-eye image. Sometimes the stereo video system reverses the parallax of near images (negative parallax) and far images (positive parallax). This is parallax inversion, also known as "reverse stereo" or "stereo inversion" Parallax inversion often occurs when switching from a PC monitor to a projector system.

How to Test for Parallax Inversion

Step 1: Power-up and view a game in 3D mode. Find an foreground object that stands just below a prominent distant object. In this illustration (left) the dashboard compass can be used as the foreground anchor and the red checkered shed is the far anchor.

Step 2: Keep both eyes focused on the foreground object. In our example you would focus your eyes on the compass. Next, cover your RIGHT eye. The far object (the checkered shed) should be to the LEFT of the compass. If it is to the right side then your system is parallax inverted.

Step 3: To double check, open your RIGHT eye and cover your LEFT eye. The far object should jump to the RIGHT. Again, if the far object is to the LEFT of the near anchor while viewing through your right eye, then your system is parallax inverted.