Did you go to bed with a headache after watching 3D TV, or after seeing Avatar or Cars 2? If so, you are not alone. 3D causes eye strain, headaches, and blurry vision according to a study published in the Journal of Vision
University of California, Berkeley researchers pointed out that producers of displays and stereo content need to understand the parameters of the conflict between what is called vergence and accommodation to determine how to best minimize distress for the viewer. In other words, educate themselves before making the viewing public irritable by foisting the latest phenomena on them.
3D, hailed as an advance in viewing pleasure, has not turned out to be so pleasurable for many people. Evidence the number of people choosing to see a release in old fashioned 2D, when a 3D version is available. Cost isn’t the only deciding factor. Trouble with 3D should alert you to the possible need for an eye exam
Approximately ten percent of people don’t have true depth perception to begin with. Many more may have trouble with their binocular vision
, which is needed to see the 3D images. To determine if you fall in this category, an eye care specialist, ophthalmologist or optometrist, can include an assessment of your stereoptic vision during your eye exam
. Viewing stereo, however, differs from optometric/ophthalmic optical corrections. People who suffer from strabismus (eyes don't align when focusing) or amblyopia (one eye loses the ability to see details) or who have problems keeping their eyes moving in tandem will have problems fusing 3D images.
The American Optometric Association (AOA) hails the 3D craze as a free eye exam. If your child, or you, are having problems with 3D images, they say it could be a symptom of an undiagnosed eye disorder
. So check it out. According to the AOA, there are three million to nine million people in the United States
with binocular vision problems. Viewing 3D TV and movies can help detect problems and open the door to treatments. If amblyopia is not detected and treated early, it often causes not only a loss of 3D viewing, but lifelong vision impairment and disability.
Samsung’s R&D center, SAIT (Samsung Advanced Institute of Technology
) joined the NIH and Grant-in-Aid for JSPS Fellows in funding the UC project. Samsung is known for their 3D HDTV products
. They offer a simplified explanation of how such a TV works
. Samsung also touts how the glasses used with their 3D TVs are a step above the competition. Something to consider when even eye wear used to render 3D viewable is thought to be another factor in viewer discomfort.
In the UC study, two areas were of concern, the focal point – the screen surface – and the vergence distance – where within the image the eyes are looking. In 3D, vergence varies and can be deeper than or thrust out of the screen. In comparison, 2D focal points and vergence are equal. The researchers discovered that how far the viewer was from the screen made a difference. Seated far away, viewers were more comfortable with images that were nearer – in front of the screen. The opposite was true the closer to the screen they sat – images behind the screen then were more comfortable. This understanding could assist producers who know how far away their audience will be – movie theater vs television vs hand held devices.Participants were asked to rate how they felt after seeing a 3D presentation
The study was subjective, similar to a survey presented at 3D Media 2010 of people in a cinema in Russia where 30 percent of those viewing a S3D film reported eye tiredness. Participants in the UC study were also asked how they felt after viewing various 3D settings. They rated such things as headache and eye strain. Twenty-four subjects between 19 to 33 years old participated.
Understanding the implications of 3D is important beyond the entertainment arena. Three dimensional displays are popping up in several applications, such as medical imaging, operation of remote devices, surgical training, virtual prototyping and vision research as in this study. Distortions are inherent in 3D images caused by, among other things, the differences in the depth of the display versus the depth of the depicted scene.
A 3% Rule for S3D cinema described by Bernard Mendiburu
states that the separation of the cameras used to generate the imagery should never be more than 1/30th of the distance from the cameras to the foreground in the scene. However, the rule only relates to the method by which the images are captured, not to how those images are displayed.
Vergence–accommodation conflict, the focus of this study, is present in all conventional stereo displays, whereas other factors are not always. Other factors, such as flicker, motion judder, visual-vestibular conflicts, and vertical vergence, need to be explored also.
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