Issue link: https://digital.copcomm.com/i/18322
n n n n Simulation For example, to create two main bad char- acters, the crew started with a generic Long- eared Owl, which was a “good” character in the Great Tree, and then made hero variations by painting the species with red and black de- signs. “We used the same model and rig with new surfacing,” Gray explains. To sculpt the various species of owls, the modelers began in Pixologic’s ZBrush, work- ing from reference photos and with concept art that showed each owl from the front and side. During the design process, the crew treat- ed each owl species as a unique model; each had its own 3D maquette with painted details. In addition, each hero character had two ver- sions. Te modelers, still working in ZBrush, sculpted one owl with its wings closed and an- other with its wings open, as if it were flying. Once those versions received approval, the modelers moved into Autodesk’s Maya. “Ultimately, we had one model and one rig, but the modelers used the perched and flying versions as benchmarks to be sure they could achieve the transformation between the shapes,” Gray says. During this process, which continued over several months, the art- ists wisely identified seven main body shapes and sizes that they eventually refined to three topologies, ending up with three models and seven body shapes. Tese models and shapes formed the basis for all the species of owls in the film, but the overall number of models still grew. “We had at least three geometries per character, and some had four,” Gray says, “a low-res version for animation blocking, another for anima- tion, a third for lighting, and some characters had a fourth version that we used for colli- sions, to smash particles against.” Most CG characters have surfaces created with 14 October 2010 Animal Logic created 70 characters for Legend of the Guardians: The Owls of Ga’Hoole, including representations of most owl species. displacement maps, texture maps, and sometimes hair and fur. Tese characters had feathers. “Te bald version of an owl is a skinny, chicken-like creature,” Aiden Sarsfield, CG supervisor, describes. “Te volume and thick- ness for the owls comes from their feathers.” Te crew created two types of feathers. Ani- mators controlled the primary feathers, which connected to the wings. Te character effects team controlled the secondary and downy feathers, which they generated procedurally. For each type of owl, modelers created 60 primary feathers, 24 for each wing, and 12 for the tail, and delivered them to the rigging team. After Happy Feet, the riggers had offered the animators a number of options for im- proving the rig, and based on these responses, they rewrote the underpinnings of the system (see “Happy Feat,” November 2006). “We kept the look and feel of the rig we used for Happy Feet,” Gray says. “But we completely overhauled the internals.” As did the modelers, the riggers needed to achieve flying and perched versions of the owls within one rig per character. Once they had developed a generic articulation structure, the riggers put each component—the wing, leg, spine, and so forth—into a library. “We rebuilt each character’s rig from the ground up using shared, common compo- nents,” Gray says. Te surfacing artists also worked with two versions of each bird, grooming one pose with the wings open in a T-pose, as if it were in flight, and another of the bird perched with its wings closed. “Te real trick in making the deformation look right was having the sur- face transition as well,” Gray says. “Animators could pick whether the feathers were neat and tight in a perched pose, or looser in flight, and the surface would transition with the character while it was moving.” Te animators had approximately seven controls on each arm, that is, the bird’s wings, and an additional 10 to 15 on the feathers. “Tey could bend and curl and cup individual feathers to simulate the force of wind,” Gray says. “On top of that, they could rotate and translate individual feathers if they wanted.” An automated review system provided ren- ders for the secondary feathers so the anima- tors could review the final performance of the fully feathered birds before the owls moved on to lighting. “We could do our reviews in context with- out involving all the departments,” Sarsfield says. “Te animators would check [the perfor- mance into the pipeline]. Te procedural ani- mators would cache the motion onto geom- etry for the performance. Te cache would be loaded overnight onto a set with the camera, and we would generate all the renders so they’d be ready for the animator the next day.” Te procedural system worked for other depart- ments as well, with each selecting the features to turn on and off. Layout, for example, might want depth of field on and feathers off. Growing Feathers Procedurally To create realistic secondary feathers and a downy surface, an R&D team led by engineer Daniel Heckenberg created a new system ap- propriately named Quill. “We rewrote our feather system from the ground up,” Gray says.