Issue link: https://digital.copcomm.com/i/110653
CG Characters post editing to approximate where the fat layer would be. Because we know genman works, we know we'll be in a good ballpark whether we're making Captain America or a dwarf. We don't have to start from scratch. We get genman, do the warp, and we're up and running." Because Weta Digital builds all creatures great and small with a muscle-simulation system, it also has a "genhorse," created in collaboration with a nearby veterinary college, and a "gendog," first created for the character Snowy in The Adventures of Tintin. "We didn't do an MRI for the eagles," Clutterbuck says, "but we found lots of repositories with CT and MRI data, and our system mapped almost one to one. We use MRI data as the basis for all muscles—real-world data that we can almost plug straight in." Gobs of Goblins The generic templates help the crew more easily set up a creature. Other tools help them duplicate the result with variations. "We wrote new tools to populate the film with characters at the same quality as the 'hero,' " Clutterbuck says. "Although we generated all the Orc and goblin variants from one 'hero' Orc and one 'hero' goblin, we don't delineate between 'hero' and 'background' any more. We build one guy and use a tool set to create others procedurally. What's cool about this is that if we change the 'hero,' the changes propagate out to all the others." The largest goblin and the one with the starring role was the toad-like but nine-foot-tall goblin king. "He had amazingly gross features, like massive wattles, that made him a lot of fun to work with and animate," Clayton says. "We polished off the rough edges from the captured body movements and made him feel big and heavy, and we added extra ideas with keyframe animation to give him a stylized motion and identity." Actor Barry Humphries provided the Great Goblin's voice; Terry Notary, the motion-capture data. Surrounding the Great Goblin, which was a unique model, is a horde of equally disgusting but smaller goblins that were surfaced, like the king, with pus and boils. To create these creatures, the crew produced 13 variants from one version fitted with a skeleton and muscles. "We do that with a script," Clutterbuck says. "We transfer the basic setup to other characters of various sizes, and warp all the muscles and skin to fit. We don't make 13 unique character rigs. In fact, when we make the 'hero' guy, we only make the right-hand side and then generate the left procedurally. We build an arm, a leg, and the right side, hook it up, and then asymmetrically warp the whole thing. There are 130 goblins in the film, and the whole build was run by two people." Similarly, the R&D department developed software for defining and creating a variety of rigged faces for characters built with a common topology. Weta Digital's JP Lewis, along with Matt Cordner and Nickson Fong, just received a technical achievement award from the Academy for the Pose Space Deformation technique, which underlies this software (see News, page 31). "The system is like a mixer," Revelant says. "You can specify a number of variations and it will automatically create that number of new characters. Or, you can drive the variations through sliders. For example, you can use 25 percent of the nose and the left eye of one, and 25 percent of the nose of another." This gave modelers the ability to design and create variations quickly. Even though the faces looked radically different, they all included complex facial rigs that incorporated 100 connected blendshapes or more. Some goblins, for example, have no nose or lips. "Other systems based on blendshapes that work this way cut from one area of influence to another," Revelant says. "But this system takes into account the surrounding area, so you never break the model. There is never an area of discontinuity. You end up with a new model, organically solved, with a new facial rig; it creates the complete blendshape tree." And, because a hero character is the starting point for the variations, each variant has enough resolution in the body and face to step into a starring role. Fat Trolls, Stone Giants Facial animation, it turns out, was the biggest challenge for the three giant, flabby, CG trolls: William, Bert, and Tom, who appear in Hobbit. "Before now, they just grunted and roared," Clayton says. "But, in Hobbit, they converse with one another, have arguments, and confront Bilbo. And, of course, there's a big fight scene with the dwarves in which they roared and screamed, so we needed good facial animation with convincing dialog." Oddly, three of the actors who played the At top, Weta Digital's award-winning "Face Mixer" software helped the crew quickly set up infinite face variations for the hordes of goblins. At bottom, the trolls use the same muscle and skin simulation system as Gollum. January/February 2013 CGW0113-Hobbit2pfin.indd 19 n n n n 19 1/31/13 5:03 PM