# Application of Three-Dimensional Vision Technology in Dance
## 2 Three-Dimensional Vision Technology
### Three-Dimensional Vision Technology Types
#### 2.2.2 Traditional Three-Dimensional Vision Technology
Early polarized light stereoscopic imaging utilizes line polarization technology, requiring the glasses to remain horizontal when viewing. A slight skew will lead to the screen ghosting and stereoscopic effect deterioration. Nowadays, it is mainly based on circularly polarized light technology, where the direction of polarization is rotated regularly, so the light transmission and blocking characteristics are almost unaffected by the rotation angle, making the viewing more accessible. Polarized light stereo imaging technology is suitable for most theaters, TV projectors, etc., featuring full-color reproduction at full resolution, extremely low crosstalk (less than 0.1% when utilizing linear filters), and no 3D vertigo or fatigue. However, the cost of playback equipment for this technology is high, and the picture brightness is significantly reduced as more than 60% of the emitted light is filtered out [11]. Naked-eye 3D technology allows for the left and right eyes to see two images with parallax from a screen without wearing any glasses or additional equipment. Stereoscopic vision is generated when the brain processes them in an integrated manner. When in a different position or state of motion, there will be a difference in the objects viewed. Since objects are considered differently in different positions or motion states, people have a stronger sense of immersion when viewing with the naked eye than with glasses-based 3D vision technology. Naked-eye 3D technology mainly includes parallax barrier technology, column lens array technology, directional backlight technology, integrated imaging technology, and plenoptic imaging technology [12]. Parallax barrier technology is a 3D vision technology that utilizes a special barrier structure on the screen to enable the left and right eyes to view images from different angles [13; 14]. As shown in Figure 6a, by placing a special barrier in front of or behind the screen and adding tiny raised vertical stripes on the barrier to separate light, the odd and even columns pixels of the screen display the left and right eye images, respectively [14; 15]. When the image is divided into two parts according to different viewing angles, the position and structure of the barrier allows for the left (right) eye to see only the left (right) image, which produces a stereoscopic effect after comprehensive processing in the brain. Parallax barrier technology has higher image clarity, a more comprehensive view field, suitable for multiple viewers, and is compatible with the established LCD liquid crystal process. However, parallax barrier 3D imaging shows low picture brightness and mutual constraints exist between the resolution and the number of viewing angles. Moreover, the viewers are required to maintain a fixed viewing distance and position; otherwise, the stereoscopic effect will be weakened. Column lens array technology utilizes a column lens array on the screen to enable the viewer's eyes to see different images [16; 17]. The mechanism is to embed a set of microlens arrays with a unique surface structure on the display. These microlenses can project the images corresponding to the left and right eyes at different angles, and each lens focuses on a specific pixel area on the display. As shown in Figure 6b, the image is split into two parts based on different viewing angles, and the viewers receive different images for the left and right eyes when viewing the screen with bare eyes [18]. Lens array technology is characterized by a more extensive range of viewing angles, a more substantial parallax effect, and higher stereoscopic sensation and comfort. However, the same problems of mutual constraints on resolution, number of viewing angles, and stringent viewing requirements exist [19; 20]. Directional backlight technology adjusts the position or angle of the light source through the hardware or software on the display device so that both eyes can view different images to realize the naked eye 3D vision effect (Figure 6c) [21].