Issue link: https://digital.copcomm.com/i/18322
Simulation n n n n “It was a massive undertaking. We worked closely with R&D almost up to a few months before delivery to get the control and features we wanted from the system they wrote.” For each bird, surfacing artists within the character effects team hand-placed approxi- mately 1000 guide feathers and defined spe- cific parameters for each feather. Te param- eters defined such aspects as how quickly the feather becomes smooth and uniform as it moves up from a scraggly base, the length, the width, and so forth. “Almost every property was a parameter that an artist could modify,” Gray says. “We had quite a number of prim vars (primitive variables) per feather—50, maybe 100—to define the look.” Quill then interpolated roughly 25,000 feathers from these guide feathers, generating all the barbs and curves on each. “We had 4.6 million individual curves,” Gray says. “Te analogy would be a fur system on top of a fur system, with hair strands coming off each in- dividual hair strand.” Te artists began with Noctus, Soren’s fa- ther. “We picked him because he is a hero character and he represented a class of charac- get a lot of variation between two feathers, say one on the top of the head and another half- way down the back of the neck, because Quill interpolated all the prim vars between the two. We got smart about placing the guide hairs to get transitions where we wanted them.” Once the birds’ performances were in place, a first pass of simulation provided basic deforma- tion and movement, with Quill adding such sec- ondary motion as wind effects. A second process worked to untangle any intersections. “We tried to do that procedurally,” Sarsfield recalls, “and it would work in some cases. On top of that, we could apply individual guide controls. Or, we could kill individual feathers.” Although all that might sound straight- forward, it wasn’t that simple. “Initially, the pose-based deformations would be nice and clean, and then it came down to how the sur- facing artists placed the 1000 guide hairs, how big they were, how long, how wide, and then how Quill interpolated them across an area,” Gray says. “It was an iterative process working our way through all those rules.” In addition to the geometry transitioning from a perched state to a flying state, the feathers needed to transition as well. By grooming each state sep- fluffy and soft, so we got away with more in- tersections. But, we’d see every little intersec- tion on the adult characters with high-contrast patterning, like the Barn Owls. So, it was a lot of work.” Fly-through “Without a doubt, our biggest challenge was feathers,” says Sarsfield. “But the other chal- lenge was the environments. We took the environments for granted at the start, but we had to step up our pipeline. We have a huge amount of detail going on—large forests, thousands of props, and expansive worlds.” Greg Jowell, who led the environments team, describes detailed rooms leading to vast, complex landscapes rendered from a bird’s-eye view that include objects the birds land on. “One of the bigger challenges in the begin- ning was deciding what we’d see from a bird’s level,” Jowell explains. “We did a lot of early work with the art department to determine if an owl flew at this average speed, how much distance it would cover and what we’d want them to see. Obviously, the film has a bit of a fantasy style, and we did things that wouldn’t actually happen that way, but for the most ters,” Gray says. Gray counted 99 versions of the high-resolution groom for Noctus on the road to perfection. “We’d do a version, check it in, and then go back,” Gray says. Once the artists decided they had the features they needed for the feathers from R&D, they moved on to the other char- acters. “We went full steam into production of the other characters to achieve the same level of detail,” Gray says. “It wasn’t that we had the lux- ury of getting one character working and then moved into production. We were delivering as- sets for blocking and pre-lighting at the same time. But, Quill development went on to the end, and the designs didn’t allow us to cheat.” As Quill generated the millions of indi- vidual curves on the thousands of feathers, it transitioned between parameters set by the surfacing artists on the guide hairs. “We would At left, the R&D department developed a new system to meet the primary technical challenge for the film: creating and moving the owls’ feathers. At right, surfacing artists re-groomed the warrior owls, giving them helmet hair to keep their feathers from poking through the helmet as they moved. arately, the grooming artists could be sure the feathers were in the right place. One of the key elements in the transition between the perched and flying states was the bird’s neck, and for this, the riggers built an automatic deformation into the rig. “Te neck would transition and deform naturally from the almost cigar/torpedo shape in flight, to the upright state where it had to bend 90 de- grees and look bipedal,” Gray says. “Also when they’re perched, they can turn their necks about 280 degrees.” To check for intersections, the crew put each character through 500 frames of calis- thenics every day for six to eight months. “It was a daily process with modeling, rigging, and surfacing,” Gray says. “Te owlets were part, the environments feel real in a stylized way because of the richness of detail.” Knowing that the story could change, the artists built the sets in layers, leaving the final polish until the cameras were set. New asset management tools helped distribute pieces of the environments to people who needed to work with them, and new level-of-detail tools helped the team manage resources. “We had four levels of detail for the forest,” Jowell says. “Tat meant the artists hand-built the trunks and stems on all the semi-hero trees so we could control the look of the species. Ten we placed procedurally grown foliage.” Te artists started working in Maya’s Paint Effects to develop the initial spread of branch- es and leaves, a technique they also used for October 2010 15