Issue link: https://digital.copcomm.com/i/196542
Motion Capture vicon's cara 3D stereo marker-based system Drawing on Vicon's long history of providing marker-based optical systems for capturing full-body performances with its proprietary cameras, the company now offers a head rig with ■ THE MARKERS ON the performer's face translate into data that can produce expressions on a digital character, thanks to Vicon's Cara system. Vicon built the rig-mounted 720p, 60 fps cameras from scratch. "You can capture faces in a body system, Elderfield " says. "That's well understood and commonly used. But, these cameras are locked to the face and close up. " Thus, rather than using the large number of very-high-resolution cameras necessary to capture small face markers within a volume designed for body capture, Cara provides a less-expensive yet accurate solution for the facial-capture part of the performance capture. "When you capture the body and face at the same time without using the head rig, it can take a lot of cleanup and editing in post, Elderfield says. "We try to extract " the same kind of data in comparable quality to what you would get in an optical volume – in a fraction of the time. " CaraLive software gives an operator images from all four cameras and control over the acquisition system. CaraPost software takes the images from the four cameras and creates a 3D point-cloud representation of the marker positions on the face. Vicon has priced a complete system at approximately $45,000. "It comes in a case, Elderfield says. "You could take " the lid off and, potentially within an hour, capture 3D points on a face. We even include a marker pen. " glenn derry – technoprops High-resolution, high-fidelity, head-mounted video-capture rig four cameras for stereo capture of markers on faces. The cameras sit on a brace that extends out several inches from the face, two on either side. Typically, the actor wearing the head rig would have markers painted on his or her face. "Cara was born originally out of work we did with ImageMovers Digital for A Christmas Carol," says Phil Elderfield, entertainment product manager at Vicon. "That predecessor had lower resolution and lower frame rates – it was cruder in every respect, really. But it captured the infinite bendiness of Jim Carrey. It became clear we could evolve that into a product that fit a broader need. " Five years later, the company introduced Cara, which Elderfield calls the most complex product the company has produced. "There have been a lot of single-camera systems around for a long time, Elderfield says. "We went for the highest " possible quality: an open, modular system from which we can extract 3D data. With one camera, you have to process and analyze the data to infer depth. With Cara's four cameras, we get good coverage and can extract 3D points based on markers placed on the face, straight off the bat. We get the 3D representation and the motion. " Although the markers provide accuracy through Cara's system, Vicon doesn't demand allegiance to its proprietary system. "The system is open to not only our background software, but to any other processing pipeline. You could capture images without markers and process through another system. There is so much going on in this area, so many approaches, that we don't force people down any road. The market isn't embryonic, but it's evolving. There are lots of ways to skin this cat. " 8 ■ CGW Sep tem ber / O c t ober 2013 Glenn Derry's name became famous when the world learned that he was the virtual production supervisor for Jim Cameron's Avatar. In fact, Avatar is the touchstone for anyone doing on-set facial motion capture. Although Derry is currently working on Clint Eastwood's upcoming film Jersey Boys, these days the company finds itself capturing actors for game developers as much or more than for film studios. "Eighty percent of our work right now is for video game cinematics, Derry says, "especially for the new console " games. About a year and a half ago, companies really started buying into the fact that they could get a more cohesive performance if they do body and face capture simultaneously. So, we're applying a lot of the same techniques we used for Avatar." Derry's group provides a head rig equipped with cameras that capture 720p, 60 fps, 1980x1080-resolution, time-code embedded, uncompressed, color video. "Our guys are on the ground fitting the helmet, making sure we're capturing good data, he says. " On set, the company typically works cheek to cheek with Giant Studios. "They do the body capture and actual facial retargeting and solving, as well, Derry says. " " And in some cases, we do the reference work. We bring our systems and plug in to theirs. We can do the same with other companies, but the bulk of our work is with Giant. " As part of the on-set facial capture, Derry's team sometimes helps a studio's makeup artists apply markers. Prior to the shoot, the team scans the actor's face, creates a vacuform