Clothes for the princess
How the laws of physics helped create an outfit for the new Disney star.
Quite often we observed a discrepancy between the movements of the drawn characters and the movements of a real person, violation of the laws of physics, but all this is in the past. The outdated technologies are being replaced by new ones that help to create perfect characters, sharp movements and ... Even the clothes of the heroes now, like reality, are amenable to the laws of physics, taking into account friction and elasticity.
When the animators of Ult Disney’s studio first dressed up Rapunzel in a dress and began to turn her in front of a mirror, she froze in a half-turn position, and the folds of her dress became rigid like armor. The filmmakers are faced with a difficulty that has long tormented multipliers-costumers.
“We decided to create a more sophisticated attire than previously possible with the use of computer graphics,” explains researcher of the Walt Disney group Rasmus Thamstrof. - But when a character moves in a loose multi-layered outfit, different layers of fabric may touch, especially when they slide one over the other. And it can cause difficulties. ”
“We decided to stop being afraid of difficulties and try to go where the directors were leading us,” adds Steve Goldberg, senior visual effects specialist, a Disney veteran with 20 years of experience. “In computer animation, the idea of ​​what is difficult and what is easy is changing very quickly. What seems impossible on one movie is done without problems on the next. The technology is developing rapidly, and in each picture we gain experience, thanks to which we move forward. ”
Instead of moderating their aesthetic needs or attracting an army of animators to handle complex scenes manually, as the creators of cartoons usually do, Thamstrof and his team decided it was time to find a new way to solve the problem.
They contacted computer-aided professional Eitan Greenspun. He became interested in this area in 2002, when he “animated” a cowboy hat falling and jumping on the floor. He spent hours studying the slow motion frames of the film and eventually found the simplest equation for expressing the interaction of variables affecting hat bounce. And they included friction, elasticity (flexibility) and the moment of momentum with which it hit the floor. Eitan then translated his equation into a simple computer code that can be used for any “flexible material,” including rubber, fabrics, and even metal sheets.
However, depicting the movements of an unusual princess dress is a difficult task. In the case of multi-layered clothes, the computer must take into account the thousands of possible simultaneous contacts. When the animation program is overloaded with data, it turns to a backup (protective, fail-safe) program that does not allow the fabric layers to create new contacts.
The previous such programs continued to move the fabric, but did not allow the mutual displacements of the layers, which created the impression of rigidity.
A few months later the team found a solution. They came to terms with the need for a protective program that would prevent new contacts, but their program allowed the mutual slip of several layers and took into account the friction that determines the speed of such a slip.
the result was much more realistic. Later, we had to move on to another solution to the problem, the development of a program to accurately predict the movement of hair, which is more difficult than the task with “tissue glides”.
Senior animator Clay Kaytis explains: “Previously, no studio had to do 20-meter hair. As a rule, hair in computer animation behave passively. They do not participate in the life of the characters, they are not dispersed throughout the room and do not wrap around chairs. We were the first to do all this. I am simply shocked by the technical level that we all achieved on this film. This is a real miracle of technology. ”
To solve this problem, we also had to involve specialists.
Ward, a computer engineer, was part of a group of three people (besides her - Marianne Simmons and Andy Milne), who were commissioned to develop software for hair styling. And this is not by chance: Ward defended her dissertation on her hair and spent the last 10 years in search of the optimal way of computer animation. She is considered, perhaps, the best specialist in this field.
Collecting information, engineers watched commercials shampoos on
YouTube and watched a model with hair 2 meters in length. Many tests have been made so that the modeling programs transmit hair movement as best as possible.
“After we realized that we can model hair, it was necessary to take into account a bunch of directorial instructions about all the contours, the bends of the hair, their movement and weight. The main thing was to learn how to do it quickly and without losing control. At the beginning of work, it took us two weeks on one frame; We later reduced this time to 10 hours, ”says one expert, and the team later added the final touches to Rapunzel’s hair, giving it a magical shine.
So that you and I could see the masterpieces of world animation, thousands of people are doing a great job, and you thought that cartoons are simple? :)
Quite often we observed a discrepancy between the movements of the drawn characters and the movements of a real person, violation of the laws of physics, but all this is in the past. The outdated technologies are being replaced by new ones that help to create perfect characters, sharp movements and ... Even the clothes of the heroes now, like reality, are amenable to the laws of physics, taking into account friction and elasticity.
When the animators of Ult Disney’s studio first dressed up Rapunzel in a dress and began to turn her in front of a mirror, she froze in a half-turn position, and the folds of her dress became rigid like armor. The filmmakers are faced with a difficulty that has long tormented multipliers-costumers.
“We decided to create a more sophisticated attire than previously possible with the use of computer graphics,” explains researcher of the Walt Disney group Rasmus Thamstrof. - But when a character moves in a loose multi-layered outfit, different layers of fabric may touch, especially when they slide one over the other. And it can cause difficulties. ”
“We decided to stop being afraid of difficulties and try to go where the directors were leading us,” adds Steve Goldberg, senior visual effects specialist, a Disney veteran with 20 years of experience. “In computer animation, the idea of ​​what is difficult and what is easy is changing very quickly. What seems impossible on one movie is done without problems on the next. The technology is developing rapidly, and in each picture we gain experience, thanks to which we move forward. ”
Instead of moderating their aesthetic needs or attracting an army of animators to handle complex scenes manually, as the creators of cartoons usually do, Thamstrof and his team decided it was time to find a new way to solve the problem.
They contacted computer-aided professional Eitan Greenspun. He became interested in this area in 2002, when he “animated” a cowboy hat falling and jumping on the floor. He spent hours studying the slow motion frames of the film and eventually found the simplest equation for expressing the interaction of variables affecting hat bounce. And they included friction, elasticity (flexibility) and the moment of momentum with which it hit the floor. Eitan then translated his equation into a simple computer code that can be used for any “flexible material,” including rubber, fabrics, and even metal sheets.
However, depicting the movements of an unusual princess dress is a difficult task. In the case of multi-layered clothes, the computer must take into account the thousands of possible simultaneous contacts. When the animation program is overloaded with data, it turns to a backup (protective, fail-safe) program that does not allow the fabric layers to create new contacts.
The previous such programs continued to move the fabric, but did not allow the mutual displacements of the layers, which created the impression of rigidity.
A few months later the team found a solution. They came to terms with the need for a protective program that would prevent new contacts, but their program allowed the mutual slip of several layers and took into account the friction that determines the speed of such a slip.
the result was much more realistic. Later, we had to move on to another solution to the problem, the development of a program to accurately predict the movement of hair, which is more difficult than the task with “tissue glides”.
Senior animator Clay Kaytis explains: “Previously, no studio had to do 20-meter hair. As a rule, hair in computer animation behave passively. They do not participate in the life of the characters, they are not dispersed throughout the room and do not wrap around chairs. We were the first to do all this. I am simply shocked by the technical level that we all achieved on this film. This is a real miracle of technology. ”
To solve this problem, we also had to involve specialists.
Ward, a computer engineer, was part of a group of three people (besides her - Marianne Simmons and Andy Milne), who were commissioned to develop software for hair styling. And this is not by chance: Ward defended her dissertation on her hair and spent the last 10 years in search of the optimal way of computer animation. She is considered, perhaps, the best specialist in this field.
Collecting information, engineers watched commercials shampoos on
YouTube and watched a model with hair 2 meters in length. Many tests have been made so that the modeling programs transmit hair movement as best as possible.
“After we realized that we can model hair, it was necessary to take into account a bunch of directorial instructions about all the contours, the bends of the hair, their movement and weight. The main thing was to learn how to do it quickly and without losing control. At the beginning of work, it took us two weeks on one frame; We later reduced this time to 10 hours, ”says one expert, and the team later added the final touches to Rapunzel’s hair, giving it a magical shine.
So that you and I could see the masterpieces of world animation, thousands of people are doing a great job, and you thought that cartoons are simple? :)
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Source: https://habr.com/ru/post/114242/
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