Issue link: https://digital.copcomm.com/i/65907
Simulation n n n n Then, artists placed collision geometry, which lined up with the animation geometry, into the fluid simulation. Easier said than done. The complex 3,034-frame shot Smythe de- scribed earlier started with animation of the destroyer buckling in half and then breaking in two. Animators moved the two pieces up through the water according to an imagined force and drew an orange sphere to represent a fireball of an explosion. That animation file then moved on to the creature department, where artists fractured a ship model and cre- ated debris, and to the effects team for water and fire simulation. "For the most part, we had a one-way pipe," Geiger says. "We had separate simulations for fire and water. We didn't couple the simula- tions because we wanted to have flexibility." For the explosions and resulting fire and Aliens! With cat-like eyes visible behind the visors of their helmets, hands like claws, and body armor, these huge, unwelcome visitors from an- other planet look human enough to be believable. "Pete [Berg] is an athlete, and he loves sports," says visual effects su- pervisor Grady Cofer, referring to Bat- tleship's director. "He wanted athletic, powerful creatures that weren't so dif- ferent from us. He wanted creatures we could relate to." On set, ILM used its iMocap sys- tem to capture the performance of stunt actors playing the aliens. Even though the digital thugs would be seven feet tall and weigh 450 pounds, the actors gave the animators a basis from which to work. "We took the essence of their performance and applied it to the characters," says Glen McIntosh, anima- tion director. "It's as if they're from a planet with a parallel evo- lution, slightly skewed. They have dirt under their fingernails." Frank Gravatt supervised modelers who worked from maquettes and concept art to create the aliens' faces and hands. "We built on technology and rigs we've had in the past, and we have a strong modeling and painting crew, but there were a lot of aesthetic challenges, and we had many revi- sions," says Doug Smythe, digital production supervisor. "We probably went through a dozen iterations on the land commander's armor alone, trying to figure out the color and patterns, whether the aliens could see through the visor, and what the visor was made of. Trying to nail down the look was smoke, the artists used ILM's Plume software, a GPU-based system. The system, widely used on previous films, allows the artists to generate quick iterations and, therefore, more easily art- direct the simulations. "We couldn't believe how quick the artists turned them around," Geiger says. "We' tach fire to debris and use debris to drive an air field. In this film, the whole was much greater than the sum of the parts." Cofer says he knew the team could make the film when they started working on a shot for the trailer of the alien ship breaching the water. "We had done a splash test with our new simulation tool set and an alien ship," he says. "We were getting scale and level of detail, but we weren't there yet. And then Pete [Berg] said he wanted the ship to breach close to the camera, with water splashing off it. So, we just d at- started doing iterations and fine-tuning. Then one day, someone tried a different parameter and it worked. And we kept elevating the work after. I think the results are astounding." By speeding the simulation process, the Battleship Water Department made it possible for the supervisors to make more creative deci- sions. "Before, we saw simulations separately in five viewings," says Pablo Helman, VFX supervisor. "Now we see everything. When you can see all [the splashes, mist, and foam] in one [simulation], you can make specific comments. It's always about feedback. And the faster we can do the simulations, the more accurate we can be to the vision we have." n Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net. Director Peter Berg wanted the aliens to be flawed characters, not monsters or superheroes, as if they evolved along a similar but slightly skewed path. Animators started with iMocap data captured from stunt actors on location and then concentrated on the aliens' hands and eyes (visible behind the visor) so the audience would know the armor-clad creatures weren't robots. far more difficult than the actual implementation." Russell Earl supervised the modelers who built the armor, which they placed on a complete body that was modeled beneath. "The armor was particularly challenging because it wasn't the same on the left side and the right side," Earl says. "So we had to build both sides individually, which added a lot of time to the schedule. We lost the advantage we some- times count on." Riggers and texture painters couldn't count on being able to copy from one side to the other, either; the asymmetry affected artists throughout the pipeline. Once animated, the aliens moved into the creature depart- ment, which hooked the armor pieces together, added steam to show the aliens' breath, and fixed any shape interpenetra- tions and cracks in the surface. At first, the director wanted to give the aliens dry skin. "Dry skin looks artificial," Smythe says. "But, he didn't want them to look slimy. " New shaders provided the creative compromise. –Barbara Robertson April/May 2012 17