High Convergence
(Target object is near)
Low Convergence
(Target object is far)
There are two primary factors to generate a 3D stereo vision, Convergence and Parallax.
The convergence is the angle formed by your eyes and the observed object. The higher the angle value is, the nearer the observed object is to your two eyes, and vice versa.
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High Convergence (Target object is near) |
Low Convergence (Target object is far) |
Therefore, when the convergence is fixed, any object between you and the convergence point will be closer to you, while the object beyond the convergence point will be farther away from you.
Please note that if the Convergence is higher then 6 degrees, which means the object is too close to you, then your eyes feel uneasy. On the contrary, when the value is too small, which means the object is too far, the stereo sensation will be lost.
The parallax images are the images passing through to your left and right eyes. All 3D stereo media contain a pair of parallax images that individually, and simultaneously, pass to your left and right eyes. This is to convince your brain that there is an existence of depth in the media.
When the target object offsets to the right in the left image, and offsets to the left in the right image, then your binocular focus is lead to fall behind the display. This phenomena is called Positive Parallax.
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Your convergence point is lead to fall behind the display. |
Positive Parallax |
When the paired parallax images superimpose on the display, then your binocular focus is lead to fall on the same display, which is the Zero Parallax.
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The L and R image lead your convergence point to fall on the display. |
Zero Parallax |
When the target object offsets to the left in the left image, and offsets to the right in the right image, then your binocular focus is lead to fall in front of the display. This phenomena is call Negative Parallax.
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The L and R images lead your convergence point to fall in front of the display. |
Negative Parallax |