How many dimensions can the human eye see? What about photos, TV, movies and Avatar?

The reason why human vision can distinguish distance is because of the difference between two eyes. People's eyes are about 5 cm apart, and nothing will have the same angle except aiming straight ahead. Although the gap is very small, it is transmitted to the brain through the retina, and the brain uses this tiny gap to generate the depth of distance, thus creating a three-dimensional sense. Although one eye can see objects, it is not easy to tell the distance between them. According to this principle, if the same scene is made into two images by using the difference between the two eyes, and then each eye sees its own image on one side, the depth of field can be stereoscopic through the retina. Various three-dimensional demonstration technologies also use this principle, which we call "polarization principle".

There are many forms of making 3D movies, among which polarized glasses method is widely used. It uses human eyes to observe the scenery, uses two parallel movie cameras to represent people's left and right eyes respectively, and shoots two movie pictures with tiny horizontal parallax at the same time. During screening, two films are respectively loaded into the left and right film projectors, and two polarizers with polarization axes of 90 degrees are respectively installed in front of the projection lens. The two projectors need to run synchronously and project the picture onto the metal screen at the same time to form a double image of the left image and the right image. When the audience wears special polarized glasses, the polarization axes of the left and right polarizers are perpendicular to each other and consistent with those in front of the projection lens; The viewer's left eye can only see the left image, and the right eye can only see the right image. The left and right images are superimposed on the retina through binocular convergence function, and the brain nerve produces stereoscopic vision effect. Show a coherent three-dimensional picture, let the audience feel that the scenery is coming, or enter the deep recess of the picture, which can produce a strong sense of "being there".