Comfort Zone

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As hinted at in the previous paragraph, an important concept in understanding the impact of 3D material is the audience’s “comfort zone”. This is sometimes called “Percival’s Zone”. It is the limit of separation that allows the audience to “fuse” – or view comfortably – the stereo images. Remember that the viewer’s eyes are focused on the screen but converged in front of or behind the screen. So, too great a disparity between focus and convergence will begin to wear out the audience as the brain tries to direct converging and focusing muscles to the same point in space.

As mentioned above, the size of the comfort zone is related to how close the viewer is to the screen. How close the viewer sits is related to the screen size. A viewer sits closer to a home screen than a movie screen. Therefore the comfort zone on a home screen is narrower that on a movie screen. (Also, a child’s comfort zone is narrower than and adult’s.)

size of the comfort zone

Generally we find in our testing at In-Three that the comfort zone for the distance theater viewers sit from the screen is about negative 10 inches to positive 2.5 inches or about 12.5 inches. For the typical distance between a viewer and a home screen (about 6-7 feet) the comfort zone is about negative one inch to positive one inch. (These inferences from our testing are supported by the work done at Berkeley by Martin S. Banks, PhD, Professor of Optometry and Vision Science; Affiliate Professor of Psychology and Bioengineering.)

Our interpretation of these physiological constraints is that the home 3D experience will be quite pleasant and in many cases certainly exciting (e.g., the Super Bowl). However it will not replace the very different immersive experience of watching 3D in a theater.