The 2D and 3D were concepts in virtual worlds such as anime and games. Two-dimensional usually referred to the virtual world on a two-dimensional plane, which was created by Japanese anime, manga, games, and other media. People could experience a wonderful world different from the real world in it. The three-dimensional world refers to the real world, which includes humans, animals, the natural environment, and so on. It should be noted that 2D and 3D are not absolute. In some works, 2D and 3D can also be crossed and converted.