2025-08-18
Visual Principles: Where Does the Sense of Depth Come From?
- The distance between human eyes is approximately 6.5 centimetres, resulting in subtle differences between the images perceived by the left and right eyes when viewing the same object.
- The brain intelligently fuses these two distinct images, calculating depth and distance information to enable our perception of a three-dimensional world.
- Naked-eye 3D technology employs this optical principle to simulate and separate these two images on a two-dimensional screen, ensuring they reach the corresponding eye respectively. This process effectively “tricks” our brain into perceiving a three-dimensional effect.
Flat display: 3D display technology methods
A. Light barrier type (parallax barrier)
Employing specific algorithms to interleave images, a parallax barrier is positioned between the pixel light-emitting devices and the module to separate the visual fields for the left and right eyes. As the viewing angles for the left and right eyes differ, this angular disparity is utilised to block light, thereby allocating distinct images to each eye. The user’s brain then synthesises these two differing images into a stereoscopic image possessing spatial depth information.
B. Columnar lens technology
The light emitted from a single pixel on the screen undergoes refraction as it passes through the columnar lens above, thereby projecting in a specific direction. Through precise calculation and arrangement, it ensures that your left eye receives a set of image pixels intended for the left eye, while your right eye receives another set of image pixels intended for the right eye. Upon receiving these two subtly differing images, our brain automatically fuses them together, interpreting depth information to create the sensation of a three-dimensional, stereoscopic effect.
C. Directed towards the light source
Core Principle: Time-Division Multiplexing and Persistence of Vision
Within an extremely brief interval, the following steps are cyclically executed:
Display right-eye image: The backlight precisely directs illumination towards the right eye, whilst the LCD panel displays the right-eye image.
Display left-eye image: The backlight rapidly switches to direct illumination towards the left eye, whilst the LCD panel switches to display the left-eye image.
High-speed cycling: The above two steps are repeated in rapid succession at an extremely high frequency.
D. 3D Light Field
Microlens array photography: A microlens array is positioned between the camera’s main lens and the image sensor. Each microlens separates light rays from different directions and records them onto the sensor. Consumer-grade Lytro light field cameras employ this approach, enabling the effect of “shoot first, focus later”.
Microlens light field display: When a device can precisely reproduce this recorded light information and project it into your eyes, your visual system perceives a genuine three-dimensional object before you, generating exceptionally lifelike stereoscopic vision. Six pixels respectively handle light rays from six directions.