Issue link: https://digital.copcomm.com/i/9706
Visual Effects n n n n textures to create new buildings in Argos. “Tis is a new Greek city, so we needed new The CG kraken smashes into a digital breakwater as digital water streams down 700 feet of its giant body, and then the monster demolishes CG buildings in the city with its thrashing tentacles. MPC’s rigid-body dynamics solver managed the destruction in these all-CG shots, which took months of development. the ground, we tracked and roto-animated the shoulder area to tightly attach the wings,” Brozenich explains. “We had to replace the upper shoulder to seamlessly blend CG skin, hair, and flesh to horsehair and flesh.” Because the horse could cover hundreds of yards in a short amount of time, MPC used an elaborate marker system and positioned wit- ness cameras along the route. “We captured the horse from these static cameras to track it in 3D space from multiple locations,” says Brozenich. “We also had Lidar scans of set pieces.” Rather than a horse that magically flew like a bird, Pegasus would build momentum on the ground and glide up in the air. Once in the air, the horse became a digital double, fully CG, performed by animators. Te enormous kraken, on the other hand, was always fully CG. It has crab-like claw legs, a human-like torso, a reptilian head, a long tail that ends in a series of smaller tentacles, and more tentacles growing out of its back. It is ar- mor-plated. When it rises from the water, the part that is above water is 700 feet tall. “Rigging was quite an effort,” Brozenich says. “We built into the rig a lot of what we would usually do in techanim [technical ani- mation]. Te tentacles used an FK solution because that was the cleanest rig for the anima- tors, but they also went through a secondary pass to add wiggle and jiggle.” To help the animators have something that large move through the city of Argos, the team attached a speedometer to the character and the camera. “Te trick was to have his perceived speed move relative to the camera move,” Brozenich says. “We tried to make something that could never possibly be real seem real.” When he rises from the water, particle sim- ulations in Scanline’s Flowline and in Maya stream water from the surface. During one 40-second shot of the creature’s full body com- ing out of the water, the compositors layered 60 particle-cache renders. When the creature’s tentacles smash into buildings, MPC’s PAPI, a rigid-body dynamics solver, destroyed the structures. Because PAPI works with the stu- dio’s Alice crowd-simulation software, they were even able to throw digital people into the mix. “We used a combination of PAPI, Flow- line, Maya, Maya plug-ins, plus shaders for the water,” Brozenich says. “It took months of development. But, this was the first time we were able to render Flowline through Render- Man, which was a huge advantage. We could use the same HDRIs and reflection maps, and the TDs could run everything through one lighting pipeline.” Te kraken battle takes place in Argos, which was partially a set piece, but largely CG. “We had one long road, a central square, and four smaller roads off that on set,” Brozenich describes. “We also had a set for a lighthouse. Te rest of Argos was computer-generated.” Te city is in a canyon surrounded by cliffs, a sort of arena that extends to a large harbor— the harbor from which the kraken emerges. Te crew based the cliffs on those in Tener- ife, but rather than the existing landscape, the artists carved a digital gorge, used photos of the cliffs as reference, built an ancient city into the cliff sides, and added a horseshoe- shaped inlet. “We photographed Malta locations to get architectural types and [locales in] Matera, Ita- ly, to see how structures would be derived and built into cliff sides, then presented storyboards to Louis Leterrier and Nick Davis,” Brozenich says. “Once they approved the storyboards, we shot individual buildings for photogram- metry.” Te crew shot buildings in Malta, Ma- tera, Edinburgh and Glasgow (Scotland), and Bath and Oxford (England)—any city with neo-classical structures—and then used the buildings, not ruins,” Brozenich says. “Te neo-classical buildings were in better shape than the old Greek buildings.” To manage the huge city, the layout team divided it into sections using London’s postal codes to identify areas in particular shots. “When we’re looking from the kraken’s head view, we see a third of the city, so we loaded that portion,” Brozenich says. “We had tens of thousands of pieces of geometry: props, trees—32,000 trees—and God knows how many canopies, market stalls, streets. And then on top of that are the crowds that we drove through Alice.” MPC has created cities and crowds before, but this time the studio took a different ap- proach. “We always knew we’d have CG shots with CG characters,” Brozenich says, “the kraken, Perseus, Pegasus, crowds, the Harpies. We wanted to make the city like any other as- set, so we lit, rendered, and treated it through the same pipeline as the creatures. Tat added complexity to the way we rendered shots, but it was part of the normal lighting process. So, we didn’t need to have separate teams on the city. Any TD could pick up and light the city just as he or she would light a character.” Whether or not these shots push the state of the art of visual effects in general, Brozenich feels the film pushed the state of the art at MPC. “We never expected to be in a position to do a 40-second, full-CG city with an 800- foot creature emerging from a CG ocean. So, in terms of the types of shots we are able to handle, it definitely pushed us. And, from a storytelling point of view, it was a great time.” It’s amazing that these studios created most of the effects in less than six months. If anyone wants a good touchstone for how far digital effects have matured in less than 20 years, comparing this remake of Clash of the Titans to the 1981 version would be a good place to start. n Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net. April 2010 25