ご存知のように、現実の世界は3次元の空間です。 時間の次元を除いて、現実の世界は、長さ、幅、高さの3つの次元で構成されています。 私たちはこの3次元の世界に毎日住んでおり、既存のディスプレイデバイスのほとんどは2次元の情報しか表示できず、人々に本当の3次元の感覚を与えることはできません。 表示されるオブジェクトやシーンに奥行き感（3D）を持たせるために、人々は3Dディスプレイ技術の研究を行ってきました。 20年以上の開発の後、非常に実り多い結果が達成されました。
Glasses-free 3D displays are widely used in various fields such as advertising, media, demonstration teaching, exhibitions, and film and television. Different from the traditional binocular 3D display technology, the naked eye 3D display has its unique characteristics of the naked eye, that is, the audience does not need to wear glasses or helmets to watch the 3D effect, and its realistic depth of field and three-dimensional impression greatly improves the audience. The visual impact and immersion during the viewing experience has become the best display product for product promotion, public promotion and video broadcasting.
However, how do viewers perceive 3D without wearing any equipment?
1. How the naked eye perceives 3D
The real world is a three-dimensional world. The images seen by the human eye when viewing objects have a side difference. The deviation between two images is called disparity/parallax. It is this parallax that enables people to distinguish the distance of objects and obtain a three-dimensional effect. According to different parallax values, parallax can be divided into positive parallax, negative parallax and zero parallax. When the audience is watching, positive parallax makes people feel that the object is deep into the screen; negative parallax makes people feel that the object is floating outside the screen; zero parallax is the boundary between positive and negative parallax, and the object is just projected onto the screen, that is, we Often said zero plane. In the summer night, the stars are far away from us. The line of sight we look at the stars is almost parallel. At this time, the parallax is close to zero. It is difficult for the human eye to distinguish the distance between the stars. Therefore, we feel that the stars are as far away from us. Three-dimensional.
The human brain is an extremely complex nervous system. It can produce a three-dimensional sensation through the fusion reflection of the optic nerve center and visual psychological response of two parallax images reflected in the eyes. Using this principle, we can display two left and right images with parallax on the monitor and send them to the left and right eyes respectively to obtain a 3D feeling.
The principle of naked eye 3D display is generally to split the image displayed on the display through a grating or lens, so that the human eye can receive different images, thus realizing 3D display. The slit grating display screens the displayed content by placing a slit with appropriate parameters in front of the display panel. After a certain distance, the light reaching the human eye can be separated, and the two eyes receive two images with parallax. In Figure 1, the human eye can see blue and green respectively, which can produce a three-dimensional effect.
