On the technical problems of movies

Detailed Analysis of the Behind-the-scenes Production of Invisible Man {X/EE}

Sony's old version of the story "The Invisible Man" fully shows the shocking power of computer stunts. In some movies about invisible people, most characters fade away until they disappear. In Hollow Man, what we see is that the body is corroded and shows up bit by bit. The mannequin in the film is not a simple shell, but completely conforms to the anatomical principle. Capillaries, cheekbones, shoulder blades, muscles and tissues are all very accurate, especially bones and muscles, reaching an unprecedented height.

Special skill photographers and actors

Before introducing digital stunts, let's first understand how actors cooperate with digital technology.

Kevin Bacon, the invisible man in the film, is a household name because of this blockbuster, but how many people know his suffering in the process of shooting behind the scenes, and the reason for the suffering is that Kevin Bacon must always wear clothes that match the background color and stand in a set position to shoot. Before giving it to the computer stuntman for combination, it is necessary to take a single shot of the background, and then use advanced computer technology to peel off the invisible part of Kevin Bacon layer by layer, and finally present an invisible man in clothes in the movie. In order to determine Kevin Bacon's appearance, Kevin Bacon had to be painted black all over, or wrapped in black or green clothes, and even painted his teeth. In addition, before shooting, he has to connect a bunch of snacks to his body, and then take countless photos with digital video to create another brand-new version of digital influence. During the scanning process, the staff often saw Kevin Bacon covered with wires.

Usage of main systems and software

Of the more than 500 shots in this film, 4 14 was shot by Sony Pictures, and 155 was shot by Tippett Studio. These mainly produce swimming scenes after the protagonist disappears, scenes in smoke and other similar scenes.

All special effects human body shots are made by Sony images, and more than 300 people participated in the digital special effects production in Hollow Man, some of which were made manually in recent two years. All their tools include Maya in Alias|Wavdfront (Maya is the main 3D software in this film), Studio Paint and Composer, Side Effects and Houdni, Pixar and Paraform software, and photo realism RanderMan. Most of them run on SGI workstations. About two-thirds of the shots produced by these Sony images contain invisible protagonists, and the other one-third are computer-generated close-ups of human bodies or gorillas. The following will continue to introduce the inside story of this technology.

SWG of human anatomical model constructed by MAYA

This film has 1 15 shots of Sebastian or Isabella, with figures. Each digital model includes: 65'227 arteries, veins and nerves (42' 303 for gorillas); 50'000 jump curve generates capillaries; 10' 000-50' 000 muscle fibers (the human body has 40'000 muscle fibers); 3' 150 models and body parts (excluding facial animation objects and close-up models); 300-400 bones; 20 organs

A team of six people made this NURBS model using Maya: while carefully measuring the actors with photos and 3d scanners, they also got the help of anatomical experts. The model is made from the skeleton, and the producer first creates the spine of the protagonist through the measurement of skin and the knowledge of anatomical experts. It is very important to determine the relative position of bone and skin, because if the position of bone is right, muscles will make mistakes, and if there is not enough space between bone and skin, muscles will pierce the skin. More than 200 muscles of the trunk must be stitched on the bone, which is very complicated because they must bend and move like real muscles. If there is a problem with the bones, it will be reflected for a long time when making the animation of the assembly model, so it is very useful to sew the muscles. In addition, because muscles need to be endowed with special materials, the shape of muscles cannot be made flat, so every muscle is a closed volume, even the small muscles between ribs are no exception.

The protagonist has a complete mouth and a very realistic tongue. Let him swallow it if necessary. All his organs have been done, such as lungs, brain, stomach, intestine and so on. The production of intestines is the most complicated, because they are closely connected with each other, and the producers do not want them to penetrate each other. For example, the circulatory system is complicated and the details are complicated, but the film only needs the circulatory system to show the shape of the whole body, and the blood vessels and muscles, organs and bones should also be intertwined.

Gorillas also use some of the same models in movies. The human organ model was copied to the gorilla and then adjusted to the appropriate size. Apart from gender, the biggest difference lies in the head. In addition to the different sizes and shapes, the heads of three-dimensional characters must look like actors, which is the only part of the whole body that is not strictly made according to anatomy. Because it is in a state of no epidermis most of the time, the producer changed the shape of muscle tissue to make this "muscle-only face" look more like the actor himself. Tm8SH

MAYA does the action of the role and the transformation of the muscles.

When an accurate human anatomy is completed, the next step is animation. Generally speaking, the production method is: control the whole body animation with bones, and compile a tool for longitudinal muscle animation. The details of the skeleton model of the protagonist must be very clear, so that the human body can be squeezed and stretched, which is very important to match the movements of real actors.

In Maya, models are used to replace the bodies of real actors by setting keyframes. When the protagonist changes for the first time in the film, the actors just switch in. When the protagonist is invisible, the actor wears a green coat, wears green makeup on his face and sticks blue dots on his joints to capture his movements. Finally, he repaired it with a brush. In order to make accurate animation, the producer added a fulcrum to the bone and added several joint markers, such as wrist, ankle, knee, neck and spine, in which the spine can move freely instead of bending in one direction. The production team also wrote a simple user interface to make the complex human skeleton animation simple, and the muscle deformation and activity were also made by Maya. The movement of bones affects the deformation of muscles, and animators must fine-tune the deformation of muscles. These data are reflected on the deformer. Team members made a facial animation system through it, and used it to make facial animation without skin. Although the technical director provided the traditional mixed model, the animator didn't really use it in the end, but only used some points above to capture the motion data. When muscle activity is adjusted, the model is almost useless. Organs are regarded as a special group of muscles, and facial tissue and muscle tissue are also completed by muscle deformation.

The situation of main production companies and the use of wr software

Of the more than 500 shots in this film, 4 14 was shot by Sony Pictures, and 155 was shot by Tippett Studio. These mainly produce swimming scenes after the protagonist disappears, scenes in smoke and other similar scenes.

All special effects human body shots are made by Sony images, and more than 300 people participated in the digital special effects production in Hollow Man, some of which were made manually in recent two years. All their tools include Maya in Alias|Wavdfront (Maya is the main 3D software in this film), Studio Paint and Composer, Side Effects and Houdni, Pixar and Paraform software, and photo realism RanderMan. Most of them run on SGI workstations. About two-thirds of the shots produced by these Sony images contain invisible protagonists, and the other one-third are computer-generated close-ups of human bodies or gorillas. The following will continue to introduce the inside story of technology.

MAYA and RenderMan color the blood and internal organs to show the feature k,

In order to control the time of invisibility and visualization, the development team used the curve panel in Maya to control the animation. They use animated control curves to fill the models of muscles, arteries, veins and bones, and make objects disappear or appear according to the characteristics of these curves. Other hidden animations, such as arteries and veins, tendons in muscles, use the DSOs technology of RenderMan (the dynamic link library of RenderMan's C or C++ language). It is a challenging task to combine all geometric fragments in different ways and describe the internal changes. The shape and movement of hundreds of groups of muscle fibers are realized by a kind of blobby in Maya. This method is also used to control the corrosion morphology of bones and skin and the blood flow in blood vessels.

In the filming process, the most difficult stunt is how to make the ambitious scientist starring Kevin Bacon gradually disappear from the audience. The audience can clearly see from the screen how a living person changes from a bloody muscle to a bone and then becomes completely invisible.