Wednesday, April 21, 2010

#3D TV disparities said to cause physical, mental strain

Stereo photographers learn to tolerate the vergence-accommodate disparity as the only way to "free view" side-by-side left-and-right images on stereographic cards. In our club about half the members have learned to tolerate this disparity and "free view" stereo cards without glasses--but the other half complain of discomfort whenever they try. Look for all 3D TVs to sport a 3D-to-2D button that lets viewers decide. R.C.J.

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.