Health & Wellbeing

Study shows 3D displays cause 'visual discomfort'

Study shows 3D displays cause 'visual discomfort'
Watch out, Barack and Michelle - recent studies have concluded that viewing 3D content causes eye strain
Watch out, Barack and Michelle - recent studies have concluded that viewing 3D content causes eye strain
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Watch out, Barack and Michelle - recent studies have concluded that viewing 3D content causes eye strain
Watch out, Barack and Michelle - recent studies have concluded that viewing 3D content causes eye strain

No, it's not just you. According to studies recently conducted by the University of California, Berkeley, the viewing of stereoscopic 3D displays does indeed cause visual discomfort, fatigue and headaches. The problem appears to come from the fact that the viewers' eyes are simultaneously trying to focus on the screen, and on objects that appear to be located either in front of or behind that screen.

The studies involved 24 adult subjects, who viewed 3D content both on small, consumer electronics-style screens, and on larger, theater-style screens. With the smaller screens, which are viewed at a closer distance, content that appeared to be located in front of the screen caused the most discomfort. Interestingly, however, viewing of the larger, more distant screens was most uncomfortable when content appeared to be located behind the screen.

"When watching stereo 3D displays, the eyes must focus - that is, accommodate - to the distance of the screen because that's where the light comes from," said Martin S. Banks, professor of optometry and vision science. "At the same time, the eyes must converge to the distance of the stereo content, which may be in front of or behind the screen."

In further studies, the team suggests that a larger number of test subjects be used, including children. The U Berkeley researchers hope that their findings could be used to establish guidelines for the positioning of viewers relative to 3D displays.

"Discomfort associated with viewing Stereo 3D is a major problem that may limit the use of technology," said Banks. "We hope that our findings will inspire more research in this area."

The research was recently published in The Association for Research and Vision in Ophthalmology's Journal of Vision.

Paul van Dinther
As an armchair scientist, I have been experimenting with screens for quite a while. Trying to plot out what factors are involved for 3D display and depth perception.
I have been following this whole 3D craze with dismay because TV builders have failed to address the fundamentals.
Stereo vision is only one aspect of 3D vision and in fact not even nearly as powerful as some other effects. Although there are many causing discomfort the light ray divergence is most relevant.
Your eye also tells you how far away something is by the amount of work it needs to do to bring it into focus. The lens in your eye bends incoming light rays so they focus on your retina similar to how a photo camera works. To get the best possible 3D effect in commercial flight simulators, they make use of collimated displays.
Consider the pixels on your LCD screen a light sources. Take a pixel and you can consider it to be a light point that radiates light in all directions. After all you want to see the screen at many viewing angles. So the light rays diverge and the lens in your eye needs to bring the rays that hit the eye together to focus on your retina.
A collimated display emits light rays that are more or less parallel. Your eyes can relax more in order to focus which is an very powerful depth suggestion.
Stereo vision and focal distance need to match in order to get rid of the worst nauseating effect. Stereo vision may suggest something is in front of the screen but your eye disagrees because it needs to focus on the screen. These two inputs are fighting each other continuously.
The only way to solve this problem is if we can build a display with an adjustable micro lens in front of each screen pixel. If we can control the light ray divergence from a single pixel in real-time then we can match the stereo vision with focal distance and finally get rid if this mismatch. Added benefit is that displays like this can be adjusted for your eyes so you can watch TV without your glasses. They would make really good computer monitors.
A pixel worth of imagery normally only contains R, G and B channels for Red, Green and Blue light that combine to any color. In addition each pixel needs a fourth channel indicating the depth of the pixel. You may find the focal depth powerful enough without the need for stereo vision. You can try this simply by closing one eye and look around and notice how your eye adjusts to things nearby and far away.
All \'3-D TV\' is doing is tricking our brain into thinking a flat object or projection actually has depth. Remember the old \'Stereo-o-phonic\' slide viewers from childhood? That slide wheel had 2 slightly different photos/slides on it. You placed it in the veiwer held up to your eyes and you left eye saw one photo and you right eye saw a slightly different one. I still remember the headaches and dizzyness after viewing a few slide wheels! This is what \'3-D TV\' is doing. Except instead of two images, you wear glasses that pick up the colours sent to make the broadcast seem to have depth. I have the feeling 3-D TV\' will go the way of big screen \'projection\' televisions went!
Barry Weingart
Well after trying out both an active 3d set - Toshiba and a passive LG set, for home use all I can say is LG passive is WAY WAY better than any active set. Especially in terms of fatigue and headaches. I am amazed the other sets are selling at all.
Ian Cockayne
As a person with vision in one eye only the whole subject falls \'flat\' .