The film’s director Jonathan Liebesman’s most famous works before were "Battle of Los Angeles" and "Wrath of the Gods". As a young director, he was curious about new technologies, which gave Pablo enough confidence. The cooperation has also become more intimate. Both Jonathan and producer Michael Bay wanted to make the four turtles as real as possible, so Pablo proposed the idea of letting four stuntman perform on set and use performance capture to complete the CG turtle. Pablo hopes to capture the face and body movements of the stunt actor as reliably as possible, while at the same time minimizing the obstacles that the equipment poses to the actor's performance and on-site shooting.
In fact, there are six CG characters in the film, namely, the four turtles, their master Sprint, and their rival Slade. Each role is composed of a stuntman (in charge of literary play) and a stuntman (in charge of martial arts). Co-play. Since the mutant tortoise is about 6 feet taller than humans, the stuntman must either stand on a 6-foot platform or wear a pair of 3-foot-tall shoes and tie two ping-pong balls 3 feet above the eyes. , Represents the line of sight position. These height-increasing devices are mainly used in scenes where tortoises interact with humans. If it is a pure fighting scene, those stuntmen do not need to be heightened. In addition, the stuntman does not need to capture facial expressions, only body movements. However, all tortoise actors have to carry a foam turtle shell on their backs. On the one hand, it is convenient to do motion capture for the turtle shell, and on the other hand, it also allows the actors to find the feeling of being a turtle. The visual effects team was worried that these turtle shells would hinder the performance of the stuntmen, but in fact they were too worried. The stuntmen can easily do backflips with turtle shells on their backs.
The big villain Slade is bigger, and there will be huge footsteps on the ground when he walks. When making some of the physical effects of interaction between Slade and the environment, Industrial Light and Magic carefully set the extent of these destructive effects, so as to highlight Slade's size and weight.
The climax of the film’s Battle of Times Square in New York was completely CG produced. The visual effects team members shot a lot of material in Times Square and rebuilt the scenes and buildings involved in the film after returning to the company. For example, the actual size of the roof of the Condé Nast headquarters is not enough to support the actual shooting of the action scene, so the entire fight is made digitally. At the same time, in order to make the audience feel that this is the real roof, the special effects staff added some iconic Billboards, air conditioners, and the like, in the end, almost 98% of the rooftops are made of CG. Special effects staff believe that this is a trend, that is, there are fewer and fewer real shots in the film. The digitally produced building provides convenience for rigid body simulation, and Industrial Light & Magic uses internal software to simulate the fragmentation of the building. The entire street is also made by CG, including the people and cars on the street.
The body capture of the CG character uses the unique iMoCap system of Industrial Light and Magic, which was born in "Pirates of the Caribbean 2: Soul Gathering Coffin" and was greatly upgraded during the filming of "The Avengers". The scarce markers have been changed into dense triangles, which means that the movement of almost any place on the actor's body can be accurately captured. In addition, the latest version of iMoCap has also placed a QR code at the actor's joints, which is to distinguish between different actors and avoid confusion of body capture data.
To make this group of tortoises as authentic as possible, it is necessary to design their own personality characteristics for them, highlight these characteristics in the film, so as to make the audience unforgettable. This means that Industrial Light and Magic has to develop a new facial expression capture system. This system called "Muse" took 2 years to develop successfully.
The helmet of the Muse system is made according to the 3D scanning model of the actor's head. Each actor has his own helmet to ensure more comfortable wearing. The two face capture cameras on the helmet have a resolution of 1280×720P and a frame rate of 30fps. They shoot the changes in the details of the actor's left and right faces respectively. Each camera is equipped with 8 LEDs to illuminate the face of the actor, so as to ensure that accurate facial expression data can be captured even when shooting in low light at night. The batteries, hard drives and wireless transmission equipment for the Muse system are all placed on the back of the actors.
Before capturing facial expressions, Disney Research’s Medusa system performed 4D facial scans (3D+time) on 5 stunt actors (excluding Slade’s actors). The actors need to make various expressions, which will be automatically generated by the Medusa system. The facial geometric grid corresponding to a certain expression. The team will check the videos scanned by Medusa 4D, select the best moments of various expressions, and input the corresponding facial meshes into the facial animation production system Fez of Industrial Light & Magic. This choice should be as pure as possible. To laugh is to laugh, and do not include movements such as squinting and raising eyebrows.
When making up shots on site and in the studio, the actors only need to wear helmets to record their facial expressions at any time. 128 marks are drawn on each actor’s face. The Muse team will use the head-mounted camera to capture the picture. Calculate the spatial position of each marker point, and then refer to the facial grid scanned by Medusa to drive the facial binding in Fez. Medusa's scanning accuracy is very high, sometimes reaching millions of points, which allows the Muse team to accurately know the wrinkles, bumps, etc. of the actor's face, so as to accurately redirect the position of the marker to the facial binding.
Since the keynote of the film is a comedy, the director will select the most pleasant part from different shooting materials to form a complete shot. In other words, the beginning of a dialogue may be shot in New York, and the second part is in Digital Domain The third part was shot in the studio of House of Moves. Sometimes the first sentence is said with a smile, but the second sentence is a very serious expression. In this case, Muse comes into play. Because the biggest difference between Muse and previous facial capture systems is that the animator can precisely control the animation curve of each part of the facial mesh.
The previous system was unable to post-edit the capture results due to fewer marking points. That is to say, the previous facial animations were more like a series of different grid shapes arranged on the timeline, and the animator could add or add on the basis of the grid. Cut some things, but you can't change the shape of the grid itself. In the Muse system, the technician will decompose the mesh expression scanned by Medusa into more than 200 blocks, and solve them into animation curves respectively, so that the changes of each block can be controlled by the Fez slider, which makes the animation Teachers can more easily manipulate the expressions of CG characters as they usually do with keyframe curves. This also brings convenience to the director and the actors, even if it is shot in segments, it can eventually be combined into the shot the director wants.
Regarding the production process of "Teenage Mutant Ninja Turtles: Age of Mutants", Pablo Helman concluded: "Nowadays, the visual effects technology has penetrated more and more into the filming stage, and we are not simply doing explosions, fireworks, etc., we are Part of the film serves the entire plot. We worked with the director, screenwriter, actors and designers to complete this film. In fact, the reason why we visual effects people are in the visual effects industry is because we want to make movies , We like to tell stories, "Teenage Mutant Ninja Turtles" gave us a good opportunity."
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