There are three main mechanisms that permit our brain to obtain information about the shape of objects in the environment and the distance to them:
- Stereoscopic (binocular) vision
In stereoscopic vision the brain recreates a three-dimensional image of an object, analyzing the differences in the images supplied by the left and the right eye. Stereoscopic vision is at its best at shorter distances and with objects whose linear dimensions do not exceed the base measured as the distance between the eyes.
Apart from the information furnished by stereoscopic vision, our brain relies on the parallax effect. When a person moves relative to the viewed object, the background objects shift with a speed proportional to the distance to their location. This is especially noticeable at shorter distances and in environments that are motionless with respect to the viewer. The person’s head may shift by one millimeter, and the image perceived by their eyes will already be different. Even if these changes are barely perceptible, and the person will take no conscious notice of them, the brain will still register them. The parallax effect supplies a steady stream of information regardless of the distance to the object.
The third mechanism, focusing, is mainly employed at short and ultra-short distances. In order to gauge the distance to the object, the brain relies on the degree to which the background is blurred as the eye focuses on the object. The closer the object, the higher the degree of curvature of the eye lens and the more blurred the background.
Aside from stereoscopic vision, the MotionParallax3D technology employs the parallax effect. At each moment in time, the viewer receives a three-dimensional projection of the viewed object adjusted to the viewer’s current position. The viewer can inspect the object from all sides as if this object was real. As the viewer moves around the object, all of the objects in the virtual scene will be shifting relative to each other in accordance with the parallax effect. The changes in the position of the viewer that ruin the 3D effect in a 3D cinema only increase the reality of the scene when using the MotionParallax3D system.
Human vision has another interesting feature. The average human brain is incapable of processing the entire volume of incoming visual information. Because of this, the brain “caches” spatial information, for example, when a person enters a room they only track the changes in relation to moving objects and any objects to which the person directs their attention. This relieves the brain from the need to process an avalanche of incoming information and frees up some valuable “CPU time.”
With MotionParallax3D systems, if the image were to be delayed or if the tracking were imprecise it would cause the brain to perceive image imperfections as aberrations in the object geometry. For example, instead of a stationary cube, the viewer will see parallelepipeds with blurred edges. The brain will refuse to accept the “reality” of such objects. In addition, if such a flawed system were to be used for prolonged periods of time, the brain will be overloaded because it will not trust the incoming information. To increase the precision of visual perception, the brain will boost its processing power, which will result in fatigue. That is why the MotionParallax3D system puts special emphasis on tracking changes in the viewer’s head position and angle.