Special effects production, virtual preview, expression capture...
These hard-core technologies help domestic films create an audio-visual feast
◎Our reporter He Liang
Recently, the movie "The Wandering Earth 2" has been screened in theaters across the country.
In the film, countless meteorites fell from the sky and fell into the city, which left a deep impression on the audience.
In addition, there are many famous scenes in science fiction movies.
For example, in the movie "Avatar", the protagonist Jack swoops down from the top of the mountain riding a mythical beast and soars freely in the sky.
So, how do these unconstrained and unrestrained scenes in science fiction movies rely on to "present"?
The answer is a new generation of film technology.
Today, a reporter from Science and Technology Daily will introduce to you the "black technology" currently used in film production.
Special effects production: create scenes and creatures that do not exist in real life
The falling space elevator, the impact of the spacecraft shuttle... In the movie "The Wandering Earth 2", the special effects of the disaster blew up the screen.
The main creative team of the film revealed that "The Wandering Earth 2" has completed more than 3,000 special effects shots. Compared with the previous film, the application of special effects technology in "The Wandering Earth 2" is more mature, and the visual effects are more Chinese-style sci-fi charm.
Generally speaking, special effects technology is concentrated in three types of movies: fantasy, action, and science fiction.
Fang Jiexin, a researcher at the China Film Science and Technology Research Institute, said in an interview with a reporter from Science and Technology Daily that these films need to create scenes, atmospheres, creatures, and wonders that do not exist in real life. The proportion of special effects technology is relatively large, and the production of special effects is also more difficult.
"Nowadays, many sincere domestic films are constantly catching up with the international advanced level in the production of special effects. Among them, the use of physical special effects (special effects makeup, special props, miniature landscapes, mechanical bionic props, large-scale disaster installations, etc.) and digital special effects (three-dimensional Special effects and synthetic special effects, etc.) domestic sci-fi blockbusters can be compared with American blockbusters in terms of special effects production." Fang Jiexin told reporters.
In the movie "The Wandering Earth 2", the most classic special effects scene is the space elevator, and many wonderful action fights also take place here.
Fang Jiexin introduced that the space elevator scene is realized by physical special effects and digital special effects. The difficulty of realizing related special effects lies in the fact that the space elevator is not always static, there are rapid ups and downs, and there are also steady states.
This requires the assistance of physical equipment such as heavy machinery, combined with digital technology to virtualize relevant scenes.
In addition, in order to capture the rapid ascent and descent of the space elevator, it is necessary to carry out the overall design and control of the light and shadow modeling at any time.
Specifically, in the early stage of shooting, it needs the control and cooperation of physical lighting modeling design and on-site lighting array DMX (data multiplex conversion), and in the later stage, it needs the blessing of digital painting and synthesis technology, and the difficulty of blending the light and shadow effects of virtual scenes beyond imagination.
In order to achieve realistic images, science fiction movies often use virtual preview technology during shooting.
Fang Jiexin said: "Virtual pre-show technology is a bit like digital twin technology in the industrial field. It uses full-scene modeling to simulate a sand table model that can be deduced arbitrarily by the director and the main creator, and previews the actors' performances in advance. Special effects, and even multiple plans can be made for effect comparison. In this way, film production will be more efficient and communication costs will be reduced accordingly.”
It is understood that the film "The Wandering Earth 2" basically uses virtual rehearsal technology in the production of large scenes, including the movements of the actor Andy Lau walking out of the sleeping cabin, which are all presented after the rehearsal, in order to "proof" the real shooting in advance ".
Expression capture: "copy" the expression of a real person to a digital double
As a "prequel" explaining why the earth is wandering, the characters in the story of the film "The Wandering Earth 2" are younger than the first one.
Throughout the film, the film's main creative team not only completed more than 3,000 scenes and action special effects shots, but also produced more than 1,000 facial special effects.
Guo Fan, the director of the film, said frankly that the most difficult special effect was making human faces.
To evaluate whether the production of facial special effects is successful, the industry's baseline is to cross the "weird valley", that is, it looks natural and not awkward.
"From a technical point of view, the difficulty of rejuvenating people is even more difficult than some 'heaven and earth breaking' special effects shots." Guo Fan said.
To make people look younger, the approach of the technical team of "Wandering Earth 2" is to obtain the performance materials of actor Wu Jing when he was young, and use artificial intelligence technology to practice the "rejuvenation" technique.
The relevant artificial intelligence model achieved more than 5 million iterations, after which it learned to change Wu Jing's older appearance into a younger appearance.
In Andy Lau's "Face Changing", the director of the film hopes to present a young appearance that is close to the audience's understanding, not the appearance of Andy Lau when he was young.
For Andy Lau's individual shots, the staff first used artificial intelligence technology to perform basic rejuvenation processing, and then performed a large number of manual repairs to present the final "face-changing" effect.
In addition to artificial intelligence technology, if you want to achieve "rejuvenation", you also need the help of expression capture technology.
"The expression capture of Andy Lau uses American DI4D technology, which is widely used in expression capture and digital human production. Film and television works using this technology include "Blade Runner 2049", "Fantastic Beasts and Where to Find Them", "Love, Death" In terms of specific operations, the actor wears a DI4D head-mounted helmet, which captures the actor's high-fidelity facial details and micro-expressions through a point-free method, and 'replicates' them to the character's digital double. The digital double of Andy Lau's character is his 'rejuvenation model'." Fang Jiexin told reporters that since the Hollywood movie "Rejuvenation", the actor's facial rejuvenation processing technology has begun to attract the attention of the industry.
In addition to expression capture technology, capture other members of the "family", such as motion capture, performance capture and other technologies, have been "hardened" in many films such as "Avatar", "Rise of the Planet of the Apes" and "Alita: Battle Angel" in recent years. , is also constantly maturing.
At the same time as the movie "The Wandering Earth 2", there is also the hit "Avatar 2".
As a well-known director of the technical genre, Cameron once again upgraded the motion capture technology in his film "Avatar 2".
"The underwater shots of "Avatar 2" are all 'dry shots' first, and then use computer animation (CG) to make up for the effect of water." Fang Jiexin told reporters that Cameron built a 90-seat stand in the studio. A large water tank of 10,000 gallons (about 3,400 cubic meters) of water simulates the seabed ecological environment as realistically as possible.
In addition, the film crew also specially created "underwater motion capture suits" for the actors to enhance the presentation of underwater sports. This set of costumes can help show the unique swimming styles of the residents of Pandora.
Although the production of "Avatar 2" is more sophisticated in terms of motion capture and facial detail processing, "The Wandering Earth 2" still shows a certain level of technical application. .
Fang Jiexin said that although there is a gap between China's film special effects production and Hollywood, it can basically meet the requirements of film production and the viewing needs of movie audiences.
We don't have to blindly imitate foreign countries, but continue to develop and iterate according to our own needs, so as to improve the application of technology.
High-tech format projection: present a clearer and three-dimensional picture to the audience
High-end production also requires high-standard presentation methods in order to better present blockbuster movies to audiences.
The release of "Avatar" in 2010 caused a boom in giant-screen movies in China.
Two years later, the 3D versions of "Titanic" and "2012" were re-screened, and my country's film market set off another 3D wave.
"3D, like giant screen, is a high-tech format of movies. The difference is that the production of giant screen films is generally completed by the plate making team of giant screen technology companies, and giant screen cameras are used. However, in recent years, films produced in this way There are not many here." Fang Jiexin said.
In addition to 3D and giant screen, there are also "members" such as immersive audio, high frame rate, high dynamic range, and wide color gamut in the "family" of high-tech formats.
In 2019, Huaxia Film Distribution Co., Ltd. launched CINITY, a high-format film projection system, which combines the seven major film projection fields of 4K, 3D, high brightness, high frame rate, high dynamic range, wide color gamut, and immersive sound. The high-tech format was the highest technical specification in the field of film projection at that time.
"In the CINITY system, 4K and high frame rate technology are used together to increase the screen size and frame rate, giving the film a better texture." Fang Jiexin said.
To explain in layman's terms, the movies projected by the CINITY system can restore the images seen by the director on the monitor to the maximum extent on the big screen.
Some shots of the movie "The Wandering Earth 2" were shot in a high-tech format that meets the CINITY system projection standards, and only in theaters that use the CINITY system can you see the high-definition high-frame rate version of 4K+120 frames.
Some movie fans said with emotion after watching the movie: "When I watched it in the CINITY hall, I felt that all the engineering structures in the movie are very three-dimensional, such as space elevators, planetary engines, etc., almost have a naked-eye 3D viewing effect. In addition, many details of the movie They can be seen very clearly.”
In addition to "The Wandering Earth 2", in recent years, my country's domestic films "My Motherland and Me", "Detective Chinatown 3", and "King Kong River" have all been released in high-tech formats, providing audiences with a better viewing experience. experience.
Among them, the movie "Win the Championship" released in 2020 is the first high frame rate movie in China. The whole movie was shot in 4K and 48 frames per second, and many useful explorations have been made in the production process and technology.
"The screening of 4K high frame rate movies not only attracted attention to 4K technology, but also stimulated the filmmakers' enthusiasm for the application of high frame rate technology." Fang Jiexin told reporters that more 4K high frame rate movies will appear in my country in the future , worth looking forward to.