Visual disparities in 3-D TV images can cause physical strain in viewers, according to recent research at the University of California at Berkeley. While proper viewing conditions can help avoid most problems--dark room, central seat far from the screen--3-D cinematographers also need to follow careful rules or risk making people sick, researchers said. A stereo viewing chair that rotates was designed by UC-Berkeley researchers to allow manipulation of visual and vestibular cues to self-motion and body orientation. The debate over 3-D TV heated up earlier this week when Samsung issued a warning about possible health effects. Even if the physical strains of 3-D are avoided, other disparities can cause mental strain akin to vertigo, according to other investigators at the University of Washington. For the emerging crop of 3-D movies that incorporate real-world scenery, movie makers have one extra job beyond those of previous animations: Minimizing the so-called vergence-accommodation conflict. The conflict arises from the fact that 3-D displays present perceptual disparities to the brain that its never encountered before, and to which not everybody's brain can adapt.
