Issue link: https://digital.copcomm.com/i/42006
Motion Capture n n n n volume, but the biggest thing was dealing with sunlight. A traditional motion-capture system couldn't handle that intensity of light. So we switched from reflective markers to the active LED system and flashed infrared light back to the cameras. We synched the LED markers to motion-capture cameras that we synched to the motion-picture camera's time code." On location, the team ran two units si- multaneously, with as many as eight actors in the LED suits: two in one area and six in the other. Approximately 80 cameras captured the action, with half in each area. In addition, four witness cameras shot the actors' hands and faces, and provided a wide-angle view of the bodies. "It was a huge amount of data," Lemmon says. "We would fill several hard drives daily. At the end of each day, we would duplicate the data, send a version from Vancouver to New Zealand, and clear the hard drives for the next day's work." Setting Up When possible, the crew would mount the motion-capture cameras permanently on the sets or stages. When the action took place on city streets and it was impossible to affix the cameras permanently, they used aluminum truss towers on rollers that are similar to those used for concert lighting. At the end of each "T-bar" across the top, the crew attached pairs of calibrated cameras. "We developed new techniques for pre-cali- brating cameras in pairs, some new math, some new software technology that we bolted onto our existing system," Lemmon says. "Also, we had new techniques for running the calibra- tion processes more quickly once the cameras were in situ. It was a big paradigm shift for our motion-capture technician." The paradigm shift reduced the time need- ed on set from the typical week-long effort for setting up, aiming, and calibrating the cameras to 20 minutes. "The setup time was really good, and the calibration was fast," Letteri says. "Some of it was due to practice. A lot was having pieces pre-rigged so we could get everything into position as quickly as possible. We tried to pre- rig the day before. If you have the space cov- ered, and you just have to move a few cameras to shoot 'over there,' the calibration is easier to deal with; you don't have to recalibrate all the cameras." On occasion, the crew ran into situations in which they needed to re-rig the entire set, but when that happened, the production needed to change gear at the same time, too, so reconfiguring the mocap setup didn't cause delays. Most of the capture volumes were inside 20- by 20-foot-square greenscreen sets that the Weta crew would later extend digitally. One of the biggest volumes, though, was the 300- by 60-foot set built on a back lot in Vancouver for the climactic sequences on the Golden Gate Bridge. On that set, the crew could capture about half the space at one time. "We had a few dozen cameras in bird houses all the way down the length," Letteri says. In addition to replacing the actors whose performances they captured on the bridge, the effects crew replaced the set with a digital bridge, put it over the water, and added the digital background of San Francisco Bay. "Capturing the performances on set was a lot of fun," Lemmon says. "It was a unique and different problem than those we normally deal with on set when we're doing visual ef- fects. We felt more integrated with the pro- duction process. A lot of the time we're there to grab data as quickly and surreptitiously as possible. In this case, there was no avoiding being part of the production. We provided the main characters for many of the shots in the end, so we had to make sure everything for principal photography was correct." Moving On In addition to Serkis, actors of varying sizes played other apes during principal photogra- phy—small people playing small apes, a large actor playing the gorilla. Six featured apes and another dozen variants star in the film. "We needed them to carry the scenes in panto- mime," Letteri says. "Andy Serkis and Terry Notary led the charge, getting everyone to look at how to perform apes." August/September 2011 13 Give Me Hair To coat the apes with dynamic hair, Weta Digital created a new, interactive fur grooming tool. "For Kong, we had a procedural system," says Joe Letteri, senior visual effects supervisor. "The new system lets us comb and groom the hair. We wanted to groom the hair directly. And, we wanted our artists to do dozens of apes. So we developed some clever software that uses curve geometry with some hardware acceleration. It's closer to being fun to use." The new system still uses guide hairs and some form of interpolation. The in- novation is in the way the artists groom the hair. "It's more of a sculpting process," says Dan Lemmon, visual effects supervisor. "We use digital brushes and combs to push the guide hairs around. The artists don't manually pull curves or use sliders. They use styling tools. They apply control with a brush rather than with parameters. It's a bit like using a paint program's brush, but the radius also takes into account direction and orientation. With each stroke, the artist changes the guide-curve position, orientation, and the amount of noise. It's a completely new tool with its own way to store a fur set for a character." The tool, dubbed "Barbershop," rides on top of Autodesk's Maya and plugs into Pixar's RenderMan. –Barbara Robertson