We’re at an interesting multidimensional crossroad in the development of stereoscopic 3D technologies, and adaptive abilities in what is commonly referred to as “human visual factors”. It is the classic interface challenge, in which developers of technologies must anticipate the extent to which the average user or observer brings the visual tools to the table to enable them to have productive, enjoyable, immersive experiences. Much of our panel discussion on the topic at this year’s annual meeting of the College of Optometrists in Vision Development in Orlando will address these factors, and you can get a brief glimpse at the topics on pages 23-24 of the program (see here).
Beginning today, and for the next few days, I’ll give you a teaser to some of the issues that will be discussed during Thursday’s panel. What’s wrong with this picture?
It’s a slide from the Video Quality Measurement Tool 3D Project. The Project takes an in-depth look at stereoscopic 3D films and critiques them based on various visual components, in this instance an unintentionally induced vertical disparity. As you watch the switch between left and right eye views, you’ll notice that there’s actually a diagonal displacement. During the presentation on Thursday I’ll be noting how we clinically detect and deal with postural skews translating into cyclovertical imbalances.
In this instance, a 2D representation of 3D projection done via cheiroscopic tracing, the image is not only vertically displaced exhibits a very obvious torque or cyclorotation. One can also detect this in space by looking closely at the tip from horizontal on red Maddox rod testing.
Part of the challenge as I see it is to determine the extent to which postural skews and adaptive head postures are purposeful and, more importantly, will be challenged by sustained viewing of stereoscopic 3D formats. Brief periods of S3D viewing may not unmask inherent binocular challenges. But the longer the view is expected to sustain depth demands that exacerbate binocular problems and/or postural adaptations to maintain binocular vision, the more likely symptoms and performance problems are to occur. While comfort criteria for binocular viewing has classically been related to horizontal fusional ranges including blur/break relationships and various criteria, comparatively little attention has been paid to cyclofusion. In considering cylinder power and axes, as well as prism vectors, these factors become more relevant.
To probe the limits of your cyclo-fusion abilities, first use your convergence abilities to obtain a third image in the center between the original two. For you non-optometrists, that means obtaining the feeling of crossing your eyes inward while looking at the white space between the two views of the forest. You’ll notice that the depth takes a bit of time to grow. There’s actually a bit of perceptual learning for depth going on in your brain while you accomplish this. Now, tilt your head slightly toward your left shoulder and see roughly how far you can go before the S3D image in the center separates or loses depth. After you’ve come back to your starting point to re-capture the S3D image in the center, see how far you can tilt your head toward your right shoulder before losing it. Is there symmetry? If not, why?