Issue link: https://digital.copcomm.com/i/17873
CGI n n n n and ensure that eye blinks were placed in just the right spots to add life and reflect what the characters were feeling. “It’s a lot of super-fine- tuning of animation timing and spacing in order to take a character’s performance some- where special,” Chen adds. One character in particular—Spike the caterpillar—proved es- pecially daunting, mostly due to the inherent complexity of this bug’s morphology and lo- comotion. With no real shortcut to animating a multisegmented rig with a complex network of IK interdependency, Chen had to hand- animate each segment, foot, and appendage to arc, overlap, and stagger properly—“another reason to avoid caterpillar characters in the future,” he says. For some of the sight gags, Chen video- taped himself performing the physical acting and poses, which he used as video reference during animation. He also used a Webcam to capture his own face while acting out every facial expression that the script required. He then turned this information into a visual li- brary and chart for quick referencing during facial animation. with bones and Maya hair for animation, and the filmmaker set up dynamic simulation us- ing turbulence fields. Later, he omitted the sim after determining that the leaves rustling in the wind were not absolutely necessary in terms of story, choosing instead to put the time into character animation and storytelling. (Te swaying palm leaves in the beginning of the film resulted from hand animation.) To produce the lush, vibrant backdrop, Chen used photographic textures of real plants mixed with procedural textures created in Maya, making sure the plants always looked hyper-real rather than merely photoreal. “It was important to establish and maintain a slightly fantastical feeling of a cartoon, while providing a rich and believable backdrop to all the characters,” he explains. To achieve a back-lit luminescence to the leaves, Chen conducted early tests using sub- surface scattering in combination with pro- jected-texture spotlighting. It turned out that a similar effect could be achieved through the careful use of the much faster translucency at- tribute of the plant shaders. images without the prohibitively long render times,” advises Chen. “Tis is especially true for independent films without the big studio production budgets.” Terefore, rather than choosing global il- lumination and photon-casting, Chen opted instead for final gathering, using HDRI for the image-based lighting. Tis created a soft bounced-light look by filling in the shadow areas while providing a warmth and richness, with realistic reflections, to the overall scene. He also chose a highly blurred HDRI texture of a sky and tree scene, which, after some color balancing, provided an ideal blend of light and shade for the desired rain forest look. After establishing the indirect lighting, Chen used mostly Maya spotlights as key, fill, rim, and kicker lights, to punch up the scene and make the characters pop and stand out from the background. He avoided any use of ambient and point lights, while occasionally utilizing area lights to quickly flood certain areas with even lighting. Hand-painted go- bos and cookies were mapped to certain key lights to cast yet another layer of richness and shading to the sets. Tis was especially effec- tive when characters would move about the rain forest environment and appear to swim through the projected shadows, just like in the real world. Chen averaged between 10 and 20 lights To save time while rigging the characters, Chen used The Setup Machine, which automates the pro- cess for some of the bipeds and quadrupeds. Other less-anthropomorphic characters, like the wasps and snakes, were rigged by hand. “Having actually gone through the physi- cal rigor of performing the film’s actions benefited the film tremendously by helping me get into the heads of the characters so I could better channel their spirit and motiva- tion,” Chen adds. “I didn’t merely animate the characters, I had to become the characters.” Environmentally Un-friendly Te environments of “Amazonia” are rife with flowers and plants. Chen modeled and tex- tured the former in Maya using a combination of NURBS and polygons, while for certain tropical plants, he used a stock model library to save time. All the flora models were rigged One of the obvious challenges of re-creat- ing a rain forest in CG is the sheer number of plants and leaves that are required in any given scene. In order to animate in real time and render efficiently without running out of RAM, Chen carefully divided the environ- ment scenes into categories of varying impor- tance—from hero and midground plants, to background plants and terrain. Te scenes, meanwhile, were lit with Men- tal Images’ Mental Ray, integrated into Maya. “In my many years of making CG films, I learned that the key to success in lighting and rendering is to always look and aim for the point where you achieve the best-quality per scene, and these were mainly spotlights. “Te ability of a spotlight to focus its cone of illumination and its falloff with a high degree of control meant there was little need for light- linking and dedicated lights, which made troubleshooting lighting problems much easier,” he explains. Spotlights were also used as dedicated kicker lights to add accents and seasoning wherever required. Shadows, mean- while, were completely depth-map-based, without any raytraced shadows. “Being mindful of the old adage ‘Keep it simple, Stupid’ certainly kept this do-it-your- self production from bloating to something unwieldy and unmanageable,” Chen notes. Post Work For rendering, Chen used Mental Ray. But in an unusual move, the entire film was ren- dered not using a renderfarm, but a squadron of energy-efficient HP notebook computers. By dividing and conquering, Chen broke up scenes into foreground, hero, background, and extreme background layers for faster and more reliable rendering. “Tis minimized the need to halt production in order to trouble- shoot memory optimization issues common in Mental Ray rendering,” he adds. Within August/September 2010 31