If you feel dizzy when watching 3D movies, will you still feel dizzy when entering the "metaverse"?

"Metaverse" is a hot word recently. If you don't mention "Metaverse" when you go out, you will feel embarrassed to call yourself a fashion trendsetter. But what exactly is the Metaverse? What can we do with it? Do you really know these? Today, Pangke will take you to explore the mystery!

The term "metaverse" originated from the concepts of "Metaverse" and "Avatar" mentioned in the foreign science fiction work "Snow Crash" in 1992. People can have their own virtual avatars in "Metaverse", and this virtual world is called "metaverse". Does it sound very advanced and professional? Let me give you an example. Everyone should be familiar with the movie "Ready Player One", and the ecology and appearance of the virtual world it shows can be regarded as a simplified version of the metaverse.

Stills from the movie Ready Player One

Shen Yang, executive director of Tsinghua University's New Media Research Center, explained: "The metaverse itself is not a technology, but an idea and concept. It needs to integrate different new technologies, such as 5G, 6G, artificial intelligence, big data, etc., and emphasizes the integration of virtual and real."

In simple terms, the Metaverse can build a virtual world through VR, AR and other technologies. In this world, we can have many avatars and experience different and diverse lives. In addition, we can also make money, and the money we earn can be circulated with the currency in our real life. Do you have a certain understanding of the "Metaverse" now?

If the two points of avatars and the circulation of real currency are a little hard to accept for the time being, then we can start with VR and AR, which build virtual worlds, and explore the magic of the metaverse~

In real life, the application of VR and AR technologies has been very extensive. From games to movies, from retail to navigation systems, virtual reality technology has penetrated into every aspect of our lives. However, it is precisely because of people's widespread application that a very worthy issue to be discussed has also been discovered - dizziness.

Where does the feeling of dizziness come from? What are the influencing factors? Let's start with the most basic 3D dizziness, and then go deeper and deeper to analyze the things about "vertigo"~

3D is the abbreviation of 3-dimension, which means three-dimensional. A photo is a flat graphic, that is, a 2D image. 3D is like the three-dimensional image seen by the human eye. First of all, we need to understand how people "see" 3D objects.

The world seen by the human eye is 3D. This is because our eyes can truly feel the distance, geometric shape, size, etc. of each object. This is a very complex presentation process.

The first is the focus of the eyes. The principle of human eye focus is the same as the optical zoom of the camera, but the human eye focuses more accurately and quickly. When the human eye observes an object, the distance between the object and the eye can be judged based on the focus distance of the eye.

Secondly, different images are seen from different observation angles. When two eyes look at an object at the same time, the left eye and the right eye see different images from two different angles. Then the brain can figure out the shape of the object through complex calculations.

Finally, the relative size of objects seen by the human eye will be different depending on the actual size and distance of the object, and there will also be geometric deformation of the object. The different distances between different positions and our eyes cause geometric deformation of objects, which is also one of the basic principles for the three-dimensional effect of images.

There are other imaging factors, such as the layering of light and shadow, the movement of the observed object and the imagination of the brain, which can affect our judgment of the distance, shape and size of the object. These factors work together to finally present the 3D effect seen by the human eye.

The 3D movies commonly seen in daily life use two lenses to shoot dual-viewpoint images of the scene, just like the left and right eyes of a person, and then use two projectors to project the images of the two viewpoints synchronously, so that the two slightly different images are displayed on the screen. At this time, if you watch directly with your eyes, the pictures you see are overlapping and a little blurry. To see a three-dimensional image, you must take measures to make the left eye see only the left image and the right eye see only the right image.

People use the light emitted from the projector to become polarized light after passing through the polarizing film. The polarization directions of the polarizing films in front of the left and right projectors are perpendicular to each other, so that the polarization directions of the two polarized light beams generated are also perpendicular to each other. The audience uses polarized glasses corresponding to the above polarized light to watch, that is, the left eye can only see the picture projected by the left machine, and the right eye can only see the picture projected by the right machine. In this way, they will see a clear three-dimensional image.

Why do 3D movies make us dizzy? The three-dimensionality of 3D movies is not produced naturally by the human eye. It requires the human eye to constantly adjust and focus repeatedly to adapt. Therefore, if we watch for a long time, our eyes will become tired, and some people may even feel dizzy.

In addition, 3D movies have realistic images and frequent switching of perspectives, which requires the human eye to constantly adjust and convey to the brain the information that the camera is constantly moving, which is contrary to the physical movement of the human body in reality. The human body is in a static state, and the brain does not receive muscle movement signals, so the brain will produce "perception errors", causing confusion in the nerve center. In addition, the sense of balance of the vestibular apparatus is disrupted, and people will experience dizziness, nausea, etc., similar to motion sickness.

Therefore, when watching 3D movies, we recommend sitting up straight and facing the screen, taking off your glasses and taking a short break after every 30 minutes of watching.

Red and blue 3D glasses filter different colors through different colored glasses to see different images. The viewing effect will be discounted due to incomplete filtering, and the left and right eyes will appear to be one reddish and the other bluish. Now there is also a new technology improvement of red, green (blue) lenses, which belongs to the spectroscopic system and has much better effect. Adding a filter wheel and a synchronization controller to an ordinary digital projector will increase the cost of the glasses, but it will increase the cost of the glasses, and it is now less used.

3D movies first appeared in the 1950s. 4D movies are based on 3D stereoscopic theaters, with performance effects such as smoke, rain, light, bubbles, smell, and scenery, so that the audience can get a full range of visual, auditory, tactile, and olfactory experiences when watching movies. In addition, the screening site is equipped with simulated natural phenomena such as lightning and snowflakes, as well as professional dynamic seats that can move in various ways, such as lifting, pitching, and swinging, giving the audience a more realistic viewing experience.

There is not much difference between 5D and 4D movies in essence, which is mainly reflected in the improvement of some equipment, such as seats. The previous pneumatic ones were called 4D, while 5D is basically hydraulic equipment. In addition, 5D adds some unique landscape decorations on the basis of 4D to make the environment more realistic.

After talking about 3D, 4D, and 5D, we come to VR and AR, which are now widely used. VR sickness is mainly caused by two parts, one is simulation sickness and the other is visual sickness. Among them, simulation sickness is similar to the 3D sickness mentioned above; while visual sickness is caused by adverse reactions of the visual system, and the influencing factors of the device itself are greater, such as refresh rate, clarity, scene ratio, etc.

At the same time, the feeling of dizziness varies from person to person, just like some people get carsick and seasick, while others don’t. Different people feel different about movement, but we can overcome visual motion sickness through continuous upgrading and improvement of technology. If one day we really have the opportunity to enter the world of the “metaverse”, I believe that through the continuous development of technology, the experience it brings us will be more humane!

Creative team: China Science and Technology Museum New Media Team

Review expert: Wang Xi, School of Electronic Information Engineering, Xidian University