Issue link: https://digital.copcomm.com/i/65907
n n n n Animation Build A Bear For years, there has been a discernible difference between real-time and pre-rendered content. However, to successfully pull off the Coke mixed-media campaign, the CG Coca-Cola polar bears featured in each segment had to look and feel like the same bears. Animal Logic, which created the pre-rendered TV commer- cials, set the visual target for all the work, sending their as- sets (models, meshes, and lighting and texture references) to Framestore and Blitz Games to match as closely as possible. This task was especially difficult since the main characters were covered in fur—a difficult process in the pre-rendered world and an even larger one in the real-time world, but one that was accomplished through teamwork. With its experience in creating game imagery, Blitz modeled the bears and the cave environment as well as generated the textures. Blitz also created the short-beat animations, while Framestore crafted the longer, pre-generated segments. Basically, the models and scenes were created like those in a typical video game, so they could be rendered in real time. Yet, the processes were quite different from those used for pre-rendered work. For instance, the shape of the fur was built into the mesh of the model, "which is unheard of in the pre- rendered world," Woods says. Also, the textures are read into the game engine, as is the shading, which is projected live from within the game engine. Lighting is also done in engine. Ren- dering happens on demand in the engine, not hours later via a renderfarm. The team at Blitz modeled the bear meshes in Autodesk's Maya, using a fairly standard setup and straightforward bipedal character rigging. They also used Adobe's Photoshop for tex- turing and Pixologic's ZBrush for sculpting. The shader sur- faces were created with in-house software. "We have our own suite of tools, including the main engine, which has proprietary production tools, including a shader editor, " says Jolyon Webb, Blitz's R&D director. For the fur, Blitz used a well-established game technique called "fur shells," whereby the artist repeatedly renders the surface farther and farther from the base layer using a noise pattern alpha-layered over the surface that produces dots. As the next layer is rendered, the alpha is eroded a little more so that the dots get thinner and thinner and eventually taper away to nothing. The dots are layered on top of one another, akin to building up a stack of coins, until a strand of hair appears. "There was a lot of work to optimize the characters so they would run in the engine, but if you look at our models and theirs, they really do look the same," says Mike Woods, Framestore's digital creative director, about the comparison between Animal Logic's pre-rendered assets and the Framestore/Blitz assets rendered in engine. Not only did Framestore and Blitz have to worry about the outward appearance of the models, but also what's inside—in particular, the rig—in order to animate the characters properly. As Woods points out, the animators were restricted to using the actual rig; these rigs could not move around or change size like they do in the pre-rendered world. "There is not as much 22 April/May 2012 flexibility, " says Wood, noting that a significant amount of R&D occurred between Framestore and Blitz to devise a rig that could be used in the game engine and one that Framestore was comfortable using. "There was definitely a learning curve for the animators here in that regard," says Woods. He notes that the FK and IK rig system separates, requiring the team to blend animations and splines in the neck and arms differently than they usually would. "We'd get clipping on the neck if we went too far, and it would overlap the shoulder, and we would have to blend that in. In a post rendered world, that doesn't happen," he adds. In the end, the artists added several FK and IK systems to the rig, but once the models were up and running, the artists could animate them in Maya as they would pre-rendered models, and deliver the Maya scenes to the game engine. "It was a nice pipeline; there was no rendering involved," says Woods. "We would have a Maya scene of a bear jumping up and doing a touchdown dance, and once we were happy with how it looked on the Blitz rig, we would send it off to Blitz and they would put it into the game engine for us and update our game-engine build we had here in the office. We could then see it textured im- mediately, so if there was clipping on the neck or if we extended the neck too far, we could adjust it based on the feedback." According to Webb, one interesting challenge of produc- ing a real-time character to match a TV spot was that on the TV side, things change up until the last minute. For games, though, a working system has to be maintained the entire way through production. "The bears continued to evolve over the four months we worked on them, and Animal Logic didn't finalize their assets until about two weeks before the game," he says. "We had to constantly keep our assets up to date, and each asset revision could mean a complete change in the rigging, skinning, and hierarchies, and then we'd have to go back and repurpose existing animations and make sure the nodes that were important in keeping some of the procedural systems would adapt to the changes. We would overlay the basic animation rig data with the informational nodes that were hooked to the game engine—the kind of things you would not worry much about in an edited video." Of course, the look did change a good deal. As Webb notes, the direction from the agency was clear and unchanging: The bears had to look engaging and constantly alive. The specifics of the bears—their size, proportions—however, were malleable and changed over the course of the project. "With a film, you spec out shots and know what you need, and you keep the sequence as a unit, so if you have to revise it later, you go back to that one animation—a character getting up out of a chair and walking across the room, for instance— and make the change," Webb explains. "With real time, you have to produce a lot of content that is blended together. So you might have walk loops, getting out of a chair loops, head- turning code—15 to 20 elements that would fit together to pro- duce the same movement. So if the shoulders of a character suddenly get wider, we have to cascade that change through all the components that will be influenced by the change. It's a typical game problem, and it surprises people if they have not encountered it before." –Karen Moltenbrey