In this blog post, we will focus on “The Ultimate Evolution of 3D: Principles, Limitations, and Commercialization Prospects of Glasses-Free 3D.”
The Background of Glasses-Free 3D
In December 2009, the movie “Avatar” stunned the world, captivating audiences not only with its story and acting but also with its spectacular 3D visuals. Audiences readily purchased 3D movie tickets, which cost about twice as much as regular tickets, and the result was the highest-grossing film of all time worldwide ($2.8 billion, approximately 3.1 trillion won). However, many people were disappointed that they had to wear uncomfortable special polarized glasses to watch 3D movies.
Due to the discomfort of wearing glasses previously used by others or the inconvenience for people who don’t normally wear glasses, improving this issue could significantly enhance the accessibility of 3D content. In fact, since most TV commercials and demonstrations use special glasses, the general public tends to associate 3D with wearing glasses.
Why Humans Perceive 2D as 3D
Before understanding the principle of glasses-free 3D, we must first examine how humans perceive 2D images as three-dimensional. The reasons for this perception can be broadly categorized into psychological and physiological factors.
Psychological factors include perspective, texture representation, and shadows; even in paintings or photographs, these elements can create a certain sense of depth. On the other hand, physiological factors include the different images actually seen by our two eyes—that is, binocular disparity.
Binocular disparity is the phenomenon where the images seen by the left and right eyes differ. For example, when an object is brought close to the eyes, the view from the left eye and the view from the right eye appear different—this is binocular disparity. By combining this physiological information, the brain determines depth and a sense of three-dimensionality.
The Difference Between Glasses-Based and Glasses-Free 3D, and the Principle of Glasses-Free 3D
The basic principle of glasses-based 3D is simple: it involves separating the images so that only the left image reaches the left eye and only the right image reaches the right eye through the glasses. While there are various methods—such as using color filters like the anaglyph method, polarized film, or active shutter glasses—they all share the common feature of using glasses to filter the images.
Glasses-free 3D aims to deliver different images to each eye without the use of glasses, and the most widely adopted method today is the parallax barrier. A screen in front of the display shows a portion of the pixels to the left eye and a different portion to the right eye, thereby delivering distinct images.
The parallax barrier allows for the creation of multiple viewing angles by adjusting the size and position of the screen, and it can be designed to display different images for each viewing angle. In addition, there are other methods, such as lenticular lenses, that display different images depending on the viewer’s position, and the basic principle is the same.
Limitations of Glasses-Free 3D and Commercial Applications
Although the principle is simple, the main reasons glasses-free 3D has not become widely adopted are issues with resolution and brightness. In the case of glasses-based systems, the screen resolution can be the same as 2D or reduced by half to accommodate two images; however, to support multiple viewing angles, the resolution is divided by the number of viewing angles. For example, if 100 people are watching simultaneously in a movie theater and a separate viewing angle is required for each person, the resolution is reduced to 1/100 or less.
Furthermore, since the viewing angles are predetermined, the viewing position must be fixed, and the image is only visible correctly when viewed from the exact position. Parallax barriers also have the drawback of reducing the overall screen brightness because they allow only a portion of the screen to be visible to the eye. This results in limitations in terms of image quality and viewing comfort.
On the other hand, in products such as smartphones, where only one person views the screen from a fixed position, this issue is relatively minor, and commercialized glasses-free products have already been released. A representative example is the ‘LG Optimus 3D’. However, in settings where multiple people view the screen simultaneously, such as on TVs or in movie theaters, resolution and brightness issues become significantly more pronounced as the number of viewers increases.
These technical limitations can be gradually overcome as display resolution and brightness improve. Ultimately, just as photographs replaced portraits, many 2D images may be replaced by 3D, and glasses-based 3D is likely to evolve into glasses-free 3D.
