Computer Graphics World

July 2009 28 n n n n CG Characters happens early in the film, a Doctor Robot that transforms from a microscope revives Megatron, the Decepticon leader that "died" in the first film, by borrowing parts from other robots. Small but Sharp Doc Bot was ILM's smallest robot, but it isn't the smallest robot in the film. Digital Domain created those, the ball-bearing- size Microcons. Matthew Butler, visual effects supervisor at Digital Domain, pro- vides the context, which centers around the All Spark, the otherworldly cube that can bring mechanical and electronic ob- jects to life—obviously a great prize to a Decepticon interested in ruling the world. "e All Spark is held under close surveil- lance by the military, so one of the Decep- ticons, called Ravage, that ILM created, spews out a bunch of [Digital Domain's] Microcons, which fall down a vent, swarm into patterns, and hatch into mean little in- sects that assemble at breakneck speed into razor-blade-like surfaces to form a character called Reed Man. He's so sharp that when he aligns his body in a particular direction, he becomes nearly invisible." Getting the little Microcons to behave properly was a complicated process involv- ing particle simulations for the tiny robots rolling around on the floor and animation walk and climb cycles stamped onto a parti- cle system that became a crowd simulation. All of this ran in Side Effects' Houdini. To create the illusion that the Microcons were climbing up and forming the praying-man- tis-shaped Reed Man, Digital Domain ran a rigid-body simulation system backward. "We knew where everything had to be in the end," says Lou Pecora, compositing su- pervisor. "We knew where everything had to be assembled in Reed Man. So, it was easier to put them there and deconstruct with reverse rigid-body simulation and then play it forward." CG supervisor Paul George Palop ex- plains: "It was a bit of a hack. Once we had a base system, we could change the way they climbed down or, in the final simulation, climbed up." e Microcons transformed into razor blades when they reached the leading edge of their original destination. "ey'd go, 'OK, I've been here for 20 frames, time to go flat,' " Palop says. "If you look at one guy, it doesn't seem like much is going on because it's a very simple behav- ior. But when you have 20,000 actors mak- ing decisions based on position, on who's in front, it's really cool." To help the animators line up all the razor blades for Reed Man's invisible moments, the technical directors wrote scripts that turned all the blades to the camera using some spring dynamics for secondary mo- tion. "We gave them a simple tool that they ran as a simulation once they had keyframed the pose," Palop says. "But, they could tone it down if it looked too heavy-handed." To light the creature, the team used a Maya-to-RenderMan pipeline. To com- posite it, they used e Foundry's Nuke. Pecora managed the depth of field in the composite, using it to help lead the audi- ence's attention through the shot. "It was a nail-biter right to the last minute," Palop says. "It wasn't the rendering time; it was the simulation that would take all day. If we wanted to change how fast the Micro- cons were moving or reveal the blades ear- lier, or move anything closer to the camera, it would take a whole day." Alice, Callous Alice e second headache for the crew was Alice. "at's just complicated stuff," says Butler. "We started on her in November, and we were still working on the shot in May. She's a pretender. When Sam goes to college, she masquerades as a hot chick and hits on him, but she's a nasty 'bot, of course. Her tongue tries to strangle him, a metallic tail comes out, and all her skin rips off and reveals the inner mechanics of a Decepticon." Because she's human at the beginning, Digital Domain needed to track the actor's moving skin and dress, and transform her into a complex array of mechanical moving plates. To do this, the team used a combi- nation of keyframe animation and proce- dural animation in Maya and Houdini. "Once we tracked her, we baked that ge- ometry as a cache for the Houdini team, and they went crazy," Palop says. "Michael [Bay] didn't know exactly what he wanted, Animators at ILM created the performance for Ravage, a catlike Decepticon, and all the other robots using keyframing; however, procedural animation built into the rig helped prevent interpenetrations. Disk Space Transformers utilized 20tb of disk space. Transformers: Revenge of the Fallen utilized 154tb. 154tb would fill 35,000 DVDs. Stacked one on top of the other without storage cases, they would be 145 feet tall.

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