Finding the Right CG Water and Fish in Nemo

鼯鼠

For Pixar's fifth feature, they digitally conquered the complex look and feel of the underwater world, with its undulating water and beautiful fish and plant life.
By Karl F. Cohen
[ Posted on June 24, 2003 ]

At first glance, Finding Nemo抯 breathtakingly beautiful underwater computer-animation looks almost photo-real. Almost. "The animals are caricatures of sea creatures," explains supervising animator Dylan Brown. "I can see how people can look at our water and say it is photo-realistic, but it is actually caricatured as well.?
The perception that Finding Nemo was intended to be photo-realistic is based on something that happened when Pixar Animation Studios was developing the project. 揙ne of the things we did early on was a series of photo-realistic tests," Brown adds. "Our technical team figured out what elements are needed to create photo-realistic water. You have a murk that is like a fog underwater. You have particulate matter that is like little bits of dust floating around the water. You have the caustic lighting coming down that dances all over the ocean抯 floor. You have light beams, and you have surface images. They designed all of the individual elements using the software that was on hand. They did tests using four ocean scenes, two above water and two underwater, to see if they could recreate real footage of the sea. The technical crew worked on it and eventually came back and showed us their work. We couldn't tell the difference between the re-created footage and the original. It blew us all away.


"We knew we could make a Jacques Cousteau-type of documentary, but that's not what we were trying to do. What we do at the studio is caricature and it would look funny to have cartoony caricatures of fish in this realistic world. We didn't want to fool the audience that they are in a real world. You have to believe you are underwater, but it doesn't have to be photo-realistic to do that.?

Although Brown calls their backgrounds believable-looking virtual sets, he maintains that they created a fantasy world predicated on the studio's trademark hyper-realism. They dressed their sets with wonderful forms made of coral and other materials. They use carefully controlled lighting and colors. Lighting is often more pronounced and colors are often richer in the film than they are in the ocean. For example, a pale blue might become rich royal blue in the film. In the real world things become gray and difficult to see as they get farther away from you when you are underwater, but in the film their water remains saturated with color.

Understanding Water
One of the trickiest problems for Pixar抯 staff was learning to communicate to each other about actions, textures and other details that are not easy to describe in the English language. A new vocabulary had to be developed in order to communicate, and technical director Oren Jacob believes they never really mastered a vocabulary that describes all the nuances of how the water should look.

鼯鼠

Once they were able to create realistic water, the art department began to request how the water in a scene should look. Jacob says, 揟hat didn抰 make things easy. They might say, 慖t抯 a little bit too confused, but what does that mean?' They were beginning to direct it aesthetically. That challenge continued right up until the last shot of the film.?/P> Pixar invited a scientist to present lectures on waves, swells and other motions. Several staff members took a trip to Hawaii in 2000 to study water and sea life. They ended up using reference footage from that trip to describe conditions above and below the surface. Jacob recalled conversations at work such as: "Remember what it was like on the boat on Thursday afternoon? I want the water like that.?Or: "Do you want it to look more like Wednesday or Friday??They found that referring back to those experiences was more useful than saying, 揑 want it more choppy than angry."

Everybody had to learn and contribute to the dilemma of solving the water communication problems. The animators also had to learn to read the surge and swell, and study how fast the water is flowing. Knowledge of water抯 behavior was needed to help them animate properly. Camera people needed to understand the effects of water on underwater photography. The lighting experts needed to learn how far away one can see underwater. They didn抰 need to build sets beyond 100 or 200 feet, since you can't see beyond that.

Learning To Animate Fish
Figuring out how to animate swimming fish was an enjoyable part of the project for Brown. Long before the animation began there were just a handful of people working on the film. Brown and seven other members of the crew took a field trip to the Monterey Bay Aquarium, where a scientist spent an entire day with them. They saw back rooms where they nurse fish and have different species that are not on display. They got to touch a lot of things. "We had fun doing that. It was a huge learning experience for us."

Their education continued when Adam Summers, a Ph.D. from Berkeley (now at UC Irvine), became their resident ichthyologist. He explained why fish do what they do and what he thought they were thinking. He explained the unusual body movements of the blue tang, which is the species represented by the memory-impaired Dory. They make an up and down motion as they swim and they rarely use their tails. Brown had noticed the movements at the aquarium, but he didn't know what they were called or why they happened.
Brown developed the movements of the animated Dory on what he had been taught. It resulted in an interesting lesson in understanding the difference between film and reality. After a screening of his preliminary motion studies, John Lasseter, the film抯 executive producer, asked him why Dory rarely moved her tail.

People have general ideas about how fish swim. They wiggle their tails and flap their fins. So when you have this preconceived notion and the movements on the screen doesn抰 support that, you loose believability. When Lasseter saw Dory swimming fast without wiggling her tail, it was physically correct for her species, but it didn抰 look believable to him. So Brown went back and added tail wiggle. He took creative license. He says, 揊ortunately we caught that early on.?/P>

鼯鼠

One of the film’s biggest challenges was learning how to turn a fish into an entertaining actor. Brown says this was difficult to figure out, as Pixar’s past features starred characters with two legs and two arms. To turn fish into good actors, Brown adds, “We had to develop a whole new bag of tricks. They were built on the same fundamentals of animation, communication, etc., but now we were dealing with fish that had no arms or legs. I know how to make a human walk sadly or happily, but how do you make a fish swim happily or sadly? Figuring all that stuff out was a definite challenge.
“We started from reality and went from there. Part of it was learning how to make gestures with fins. If I’m underwater and I move my hands up, my body is going to move back. If our fish are gesturing all over the place, do we want to have their bodies move all over the place too? Probably not. We needed to find the right balance of getting the fish to make the right acting gestures without having the gestures throw you out of the realm of the aquatic world we were creating.”


They spent a lot of time studying Bambi (1942), as it didn’t use a lot of anthropomorphic animals. Disney really stayed true to nature. Pixar knew they didn’t want to make human-like fish that stand on their tails like the star of The Incredible Mr. Limpet (1964).

To get fish to act, Pixar had to take liberties. In Finding Nemo the face becomes very expressive. They humanized the faces in the characterization process. There is lip synch. Brown says, “We have more of a human face on a fish. A fish’s face isn’t that compelling. A real fish doesn’t have flexible lips, just a hard membrane.”

The bodies of the fish are more realistic. “A fish is really just a head with a tube thing stuck on to the back of it," according to Brown. “That’s your main silhouette and communication piece.” To maintain the look they wanted, they decided they didn’t really need to use a lot of body gestures. When they did need to use fins like arms to convey emphasis, they tried to find moments when there was a motivation for movement so the gesture would be part of a physical act. It would become a body accent and not an out of place movement.

One of the great moments of the finished film for Brown is the sequence they call “Goodbye Dory.” It really tested the animators’ ability to make fish act as it is an emotional charged scene in which the new friends part. He said, “You animate to the voices, and the reads we got from Albert Brooks and Ellen DeGeneres were absolutely on the money. Three people, Gini Santos, Dave DeVan and Mark Walsh worked on it. It was a pivotal scene… such sweet and sincere animation. It shows what we can do when we have impeccable writing, reads and just fantastic animation."

Brown believes the scene is so well done that people will probably not notice the excellence of the animation and acting. He says, “One goal of the animator is to make the craft of what you have done transparent to the audience. You want them engulfed in the film, absorbed by seeing the scene, empathizing with the characters, being entertained by them or the story. You don’t want them thinking about the craft of the animators.”

鼯鼠

Animating about 77,000 jellyfish was quite a challenge for both the technical crew and the artists. With jellyfish nothing is static, everything moves. Water, wind and their swimming movements influenced their forms. That resulted in every frame being a different composition so it was hard to create actions and forms that matched up from shot to shot. Past Pixar features starred characters that looked the same from shot to shot and their movements and appearances were easy to match up. Now they had to deal with ever-changing forms.

To create shots that matched up, they had to create key elements by hand. To avoid confusing the audience, they animated parts of 1,200 jellyfish. They were carefully placed in the foreground or middle ground of scenes so the cuts would look natural to the audience. Brown says, 揥e did those scenes three or four times before we got them right. It was so hard."

Procedural animation (movements created by computers) was used with the jellyfish. There are three parts to each animal, the bell that can float on the surface, the tentacles, which are the stinging parts that hang down from the outside of the bell, and the "oral arms," which look something like drapes of cloth that hang down from the center of the bell. (The oral arms pull the pray up into the mouth.) While the bell was sometimes hand-animated, computers automatically moved the stuff hanging off of the bell.


To create the computer-controlled movements they had to start by hand animating the basic shapes. Then the technical crew took the basic drawings and created three controls that could be used to adjust movements to get the desired random, natural look. The team could control speed, amount and offset. By adjusting the time and amount of each pulse of different animals, they created the random, natural feel to the scenes. Brown is glad they could get a hand feel to their work without having to animate 77,000 jellyfish by hand.

Procedural animation was also used to get the back and forth movement of the coral that is created by water as it surges and swells, and the movements of anemones were about 95% procedural. The anemone movements are actually similar to the movement of Sulley抯 hairs in Monsters, Inc. except gravity is turned upside down and the new effect is called buoyancy.

鼯鼠

Brown is proud of the work they put into the development of the fish and he believes they created good humans, birds, crabs and other creatures. The accomplishment that he says was the hardest to achieve was being able to do water really well. “Water is the hardest thing to do in computer graphics. In the sequences with the whale there is splashing water going everywhere. It works so well. I don't know if it was more than we could chew, but we certainly bit off a lot. It was enough to make us really nervous going into the picture, but we knew we would come out OK. We expected to figure out a lot of stuff. That is why a lot of us work here. It's a challenge and we want to conquer it.”

According to Jacob, Pixar normally trains their animators to use the technical tools so they can control all the parameters of animation. But when it comes to the most difficult shots, there are experts on the staff that are called upon to solve the problems at hand. It was Martin Nguyen, who did the actual work on the series of shots of the whale. Jacob says Nguyen spent almost a year animating "some of the most heavy duty, difficult shots of the film.”
When Jacob first saw the film’s storyboards he wasn’t sure if they could do those shots successfully, but when Martin showed us his tests, "they were absolutely gorgeous." But the greatest moment for Jacob was when he realized they had mastered the most difficult shots.

In one memorable scene, the whale’s tongue rises up and throws thousands of gallons of water up in the air and against the baleen in its mouth. Water splashes everywhere and then falls back into a pool at the bottom of the mouth. Jacob says it was difficult to get the physics of the shot to look right. It was hard to simulate, it was hard to direct, it was hard to control and it was hard to generate the needed data. “I think the splatter in the film was the most important effect we did.”

Other Great Moments
There were other difficult shots that required exceptional water treatment. He is extremely proud of a sequence created by Erik Smitt just a few weeks before the production came to a close. In the scene, a group of fish are descending back into the water. The camera goes from above the water and plunges underneath it. When he first screened the shot with people who had helped engineer it, the quality of their efforts took them by surprise. “Nobody knew exactly how we did it. That’s an amazing shot.”

There were other great moments for Jacob during the production. One was seeing for the first time the shot where a bag of water breaks on a dentist’s tray. Another came two years ago when Ken Lao and Bill Reeves first showed their test footage to see how closely they could duplicate the look of four photographic shots of water. They had been working on the project for several months. Jacob says, “I’ll never forget the day we presented their work and you couldn’t tell the difference. They just nailed it."

  

Pixar wanted Finding Nemo to combine photo-realistic water with caricatured fish.

But for Jacob, the most satisfying moment was early in 2003, after the showing of the nearly completed film at the ShoWest exhibitors convention in Las Vegas. "I’d been buried in technical stuff, getting murk to work, getting ocean surfaces to work…They understood what Andrew [Stanton, the director] was trying to do… and it communicated to them…. It indicated that all our work was serving its purpose. The audience wasn’t questioning our work, they were accepting it and moving on to the story and watching the characters evolve.”
Dylan Brown, a former animation student from San Francisco State, was hired by Pixar in 1995 to work on the Toy Story CD-ROM. He worked as an animator on A Bug's Life (1998), was one of two directing animators on Toy Story 2 (1999) and was an animator on Monsters, Inc. (2001) before working on Finding Nemo.

Oren Jacob has been at Pixar since 1990 when he worked as an intern on a Macintosh software project. He quickly rose in the ranks to become a technical director on several of the computer animated TV commercials Pixar did in the early 1990s. Pixar then moved on to create animated features. Jacob worked on Toy Story (1995), A Bug's Life (1998) and Toy Story 2 (1999) before Finding Nemo.

Karl Cohen teaches animation history at San Francisco State (Dylan Brown was one of his students), is the author of Forbidden Animation: Censored Cartoons and Blacklisted Animators (McFarland, 1997), is president of ASIFA-SF and is a frequent contributor to Animation World Magazine.

Note: Readers may contact any VFXWorld contributor by sending an e-mail to editor@vfxworld.com.

飞天猪古力

-_-||||晕~

鼯鼠

别晕，猪古力mm帮忙翻译一下吧～～～～～～～

飞天猪古力

不是吧~~老兄-_-||||这么多~~开什么玩笑阿~??

我还有别的事要做的阿~~

鼯鼠

hehe,也就算便说说

飞天猪古力

你给你这张帖原先的位置我吧~

我看情况再说~

鼯鼠

www.awn,.com上面的广告条

飞天猪古力

汗~那条条老在变~不找啦~
手忙脚乱ING~ 晕~

momotea

哈哈哈哈~~~~~~~~~~~~~把猪猪吓坏了~~~~~~~~

看来是个好帖子~