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Human Factors

Traditional stereoscopic 3D displays present two different images with horizontal disparity correlating to the spatial displacement between the left and the right eye. Each eye is given a different image and the brain fuses them to form a 3D image. This fusion process done by our brain is called Binocular Fusion. There are several factors that can cause stress and fatigue to the visual system while viewing 3D images. This is primarily related to how the human visual system interacts with the stereoscopic displays as well as stereoscopic image and content production.

Major brands have acknowledged the safety concerns of stereoscopic 3D with various warnings on their products:

Warning from other 3D stereo products

Side effects such as headaches / fatigue can occur due to:

1) Stereoscopic display technology interaction with human visual system:
  • Vergence-Accommodation conflict
  • Asymmetrical Binocular Combination
  • Interpupillary distance “mismatch”
  • Vision Disorders (Stereo Blindness, Strabismus, Amblyopia, etc))
  • Age sensitivities (Children with visual systems still developing, accommodative ability deteriorating with age)

2) Stereoscopic content generation:
  • Vertical disparity
  • Keystone distortions
  • Shear distortions
  • Cross Talk
  • Picket Fence and Image Flipping

A user can view the MLD® and perceive depth through natural binocular disparity without the need for different images to be specifically directed to each eye artificially (which is how most 3D stereoscopic display technologies work). The human visual system functions as naturally as it does in the real world for depth perception, as the front display layer is physically closer to the user than the rear layer display. This also means that the user has real motion parallax from head movements with objects on the front and back layers. This is an important depth cue for depth perception. Users can perceive an even greater sense of depth when real depth between the display layers is coupled with monocular depth cues.

  • MLD® does not suffer from side effects as proven by its market adoption in Casino and Pachinko (i.e: players view this for hours at a time).

  • There is no vergence-accommodation conflict as the vergence and focal distances to each image plane is always the same on MLD®. The 3D effect comes from real-depth and the imaging algorithms.

  • MLD® presents foreground / background naturally to the human binocular system so asymmetrical binocular combination, interpupillary distance “mismatch” are not issues – i.e: the brain is not forced to fuse two images that are not natural.

  • MLD® has real motion parallax, which means it continues to provide depth cues to those that are stereo blind.

  • MLD® is safe to view for children as it is a natural way of presenting depth – i.e: the depth is there in the display as it is in the real world.

  • Even poor stereoscopic content generation (Vertical disparity, Keystone distortions, Shear distortions, Cross Talk, Picket Fence and Image Flipping, etc) can be corrected visually on MLD® as the content converts to a natural foreground / background split so the eyes will not see these conflicts as they are presented in left/right format on a stereoscopic display.

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