Issue link: https://digital.copcomm.com/i/65907
n n n n Simulation Ships and Shredders Modelers at ILM received McNeel Rhino files from the film's art director, Aaron Haye, for the alien battleships and flagships. "Aaron used to work in the ILM mod- el shop," says modeling supervisor Russell Earl. "The designs came to us fairly complete." For the US and Japanese destroyers, the artists used photographs of the current Arleigh Burke class of destroyers, as well as photomodeling, as a starting point for the models. "We then did some in-shot work to align our CG versions to the plates taken during the RIMPAC exercises," Earl says. For the interiors, the modelers matched the sets. The USS Missouri was the most challenging ship. For this, the modelers had a 3D scan of the entire dry-docked, World War II battleship. "It was a raw cloud of points," Earl says. "There was one point for every 20mm of the 900-foot-long ship; a lot of data. So, we did a loose processing, not a detailed mesh." The filmmakers towed the ship out of the dock and into open water for some shots, and for those shots, ILM replaced the water with digital simulations to make it appear as if the ship were moving. Modelers also added moving parts—a radar dish and gun turrets. But, some of their most difficult work was in building detailed, damaged versions of the ship. "We tried to find a balance between hav- ing a model detailed enough to sell the look and having a model that could still get rendered," Earl says. "We didn't model all the teak boards on the deck, for example. They're only a few inches wide. But we did model some of the boards around a damaged area." As for the shredder, although it looks complex, the repetitive design meant it was relatively easy to model. "It has lots of little blades, and each one has con- trols so you could get a different feel," Earl says. "But, it's so repetitive; we could copy the blades and stack them up. The difficulty was in achieving the look." –Barbara Robertson of the surface back together, but because we are processing all the parts of the surface dif- ferently, they could easily be multi-threaded; we could send them off to their own core. So, suddenly, the surface reconstruction became much faster, as well." Because the other teams would render the hard-surface objects, the environments, and the creatures in Pixar's RenderMan, and be- cause he has worked with RenderMan for years, Geiger stayed with that program— Version 15, which was available when they started—to raytrace the water. "We had various ways of cheating," Geiger "You just pick the least difficult." To help speed production, the crew used "There's never an easy way," Geiger says. pre-baked animation cycles and pre-baked simulations in distance shots, and sometimes shading techniques within RenderMan to create water without running the simulation. "We initially came up with the idea for Pirates 3," Smythe says. "We use a noise modulation in the displacement, and then by animating the bands of noise modulation, you can get something that looks like flowing water. You have to make sure the space you're computing in is correct, though, so if a ship flips over, the water still flows downward. In Process Animators started the process by keyfram- ing the ships through the water. "That drove every thing," Geiger says. "They had to be aware of how a ship moves." Although a few shots were completely synthetic and the alien ships were always CG, most of the shots start- ed with something real. The alien ships had the biggest performanc- es and generated most of the simulation work. "They are 500 feet long and weigh 50 tons, and they can jump," says Glen McIntosh, ani- mation supervisor. "We needed to build char- acter into what we were animating." The destroyers were often real, filmed dur- low-resolution representations of all the ships in a scene, either matching ones in a plate or using representations of ones we' ing RIMPAC naval exercises, with CG ships added or replacing those in the footage. "Gen- erally, we' d do a layout pass that would place Smythe says. "That layout would include the water plane, the camera matchmove, and the horizon line. Then, if that was all we needed, the layout team would animate the ships according to the storyboards or post-vis." That layout then went to various places in the pipeline—the lighting TDs, the water simulation team, and the effects TDs creat- ing explosions, debris, and other simulations. When the ships did little movement and when they were in the background, the full water simulation wasn't required. But, the alien ships were often part of the action—the Stingers, for example, jumped out of the water like water bugs, causing water to stream off the sides. d add," says. "For example, to avoid fully raytracing all the geometry, we'd run a pre-pass, where we essentially calculated the thickness of the water at each point in the sea to know how much volume of water a ray would pass through. Often, explosions, not the sun, were the brightest lights. So, we'd cache out illumi- nations of explosions and use them to scatter light. That way we got the global illumina- tion and still persuaded RenderMan to run." But, if he had switched to another renderer, he would have had integration problems with the other elements. 16 April/May 2012 The shredders spinning above look complex, but their size and symmetry made them easier for the ILM modelers to create than the highly detailed, 900-foot-long USS Missouri or the much smaller but asymmetrical body armor for the aliens.