Issue link: https://digital.copcomm.com/i/19812
n n n n 3D•CGI At top, animators learned that if they showed Megamind enjoying himself while capturing the city, he became more appealing, a necessary trait for a villain who stars in a film. At bottom, Megamind’s lair was nearly as complicated an environment to create as was the city. rather than modeling a few dozen buildings to replicate and place in v arious configurations, the artists decided to constr uct the buildings procedurally. “We w ent with this appr oach because w e were really concerned about r endering a city,” Denis says. “We had never built such a big set, and we wanted to be sure we could change it at will.” Tey wanted, for example, to easily allow the crew to shorten a tall building if the dir ector noticed that it cast a shadow on a character. For each block in the city , the cr ew first mapped large areas with buildings of a particular type and height. “We had to find the rules that make a city look like a city ,” Denis says. “Cities have an organic aspect, but they ’re organiz ed. You don’t want too much v ariation.” Te team based the maps for Metro City on Paris, creating, in effect, arrondissements (neighborhoods) that spiraled out from the center. Jonathan Gibbs, who had been chief effects architect on Monsters v s. Aliens, supervised the city dev elopment, wor king with gr oups fr om the art department who helped define the design and architectural rules that created windows and other details in the right pr oportions for various building sizes and styles. “Ten, some of the ef- 14 November 2010 fects ar tists cr eated a language to describe the buildings,” Denis says. “Te advantage we had by going with the pr ocedural approach is that we could manage the siz e of the buildings. We could decide to make a building wider or taller at any point in time. We could also manage the level of detail in the model, the sur face, and the textures.” Te procedural system worked so well that the crew ended up creating fewer hero build- ings than planned. Because the pr ocedural ar chitecture had a consistent UV str ucture, the ar tists could switch textures at any time. “ We could easily make a building out of concr ete that effects needed to blow up,” Denis says. For such demolition, the effects crew created a system based on the B last Code plug-in for Maya. “It took nine months of preparation,” Denis says. “We knew we had a lot of destruc- tion, and we wanted to be sure we had some- thing ergonomic enough for the effects artists to use. We looked at a lot of footage of building demolition, really looking at it to see the r e- sponse, the size of the detail.” Te system works with texture maps to define the shattering. Shaders written in the studio ’s proprietary rendering system managed the baked textur e maps and cr eated v olumes inside the build - ings. “We wanted to be sur e the windo ws didn’t have mirror-like reflections,” Denis says. “We wanted to always see something inside, so for each window, we could have a code that defined the volume behind. As the camera moved, you’d have parallax and y ou’d see the city come aliv e. A t night, w e bar ely had to light the city because of the lights that ar e on in the interiors.” Also, cars driv en with M assive added lights—headlights, taillights—to the nighttime city. “Massive was v ery successful for the cars because it’s a procedural simulation, and that’s what traffic is all about,” Denis notes. “You de- fine some rules and go. But when we’re really far above, we just generate par ticles of light. Light is always moving in the city. It was some- thing we were especially concerned about.” Rather than tr ying to place hundr eds of thousands of individual lights in the city , the lighting artists used point-based global illumi - nation as a bounce element. “ We could light the street and get light bouncing back from the buildings,” Denis explains. “I t was expensiv e, so we rendered layers to manage it in composit- ing, which isn’t the way we usually work. But, it was inter esting for the night sequence. ” Al- though the studio relies on a proprietary com- positor, the compositing ar tists wor ked with Te Foundry’s Nuke to polish the images. In addition to cloth simulation and envi - ronments, the ar tists on Denis’s team created more typical effects—fire, dust, smoke, and other atmospherics. “We used a lot of 3D sim- ulations and a lot of particles with 3D textures for detail,” Denis says. “For fire, we used a 3D volumetric simulation. Te effects are almost characters, but this is not a car toon. We really wanted the dramatic action sequences to be tangible, to feel big and danger ous. And, the best way to tackle that is to use a lot of fluid simulation to get the details.” In addition to being able to turn the genre upside do wn, this type of r ealism, evidenced in mo vement and detail rather than in phot orealism, is another r eason why M cGrath enjo ys cr eating a super - hero movie in CG rather than liv e action. “When y ou look at a liv e-action superher o movie, y ou kind of kno w when the effects turn to CG,” McGrath says. “B ut, when the entire world is CG, y ou never feel like y ou’ve switched to a new world. Characters can even do their own stunts. Tat’s really exciting.” n Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net.