Chappie, the adorable sentient police bot (voiced by Sharlto Copley, who also donned the gray suit on set for “the poor man’s mocap”), represents this year’s Baymax or Groot. And one of the best moments is the “Real Gangsta” scene (watch below), in which he transitions from awkward toddler to cool struttin’ teenager. VFX supervisor Chris Harvey of Vancouver-based Image Engine explains how they did it.
With “Chappie,” South African director Neill Blomkamp returns to more intimate social commentary about violence and oppression in Johannesburg. And in adapting his 2003 short about an autonomous robotics company, he embraces the larger issue of re-introducing innocence and love through the AI-driven police “scout.”
Thus, Chappie was designed in a cost-effective way for police enforcement so that he could move through doors, fire weapons, and drive vehicles. He had to be badass enough to be taken seriously by criminals but also empathetic to viewers.
Image Engine got involved in the build of Chappie in collaboration with Weta Workshop six to eight months before the shoot, which is pretty unusual because obviously the practical build usually drives the digital build. “In this case, it was a little bit different,” Harvey explained. “Neill gave some concept art for Chappie to us and we fleshed that out in three dimensions, well before Weta had to build the practical model. This allowed Neill to play with it digitally and to make quick changes. But also the movement felt like Sharlto’s performance. We needed to make sure that Chappie’s ‘physiology’ could line up very well to Sharlto’s. So body proportions, joint placement made it a lot easier to mimic his performance and translate well onto the robot.
“In addition, we spent a lot of time working out the physical mechanics of Chappie. He’s built without any cheats because we worried about pulling the audience out of his believability. And so Neill didn’t want to use ball joints. He wanted to use known, mechanical systems that were all very familiar, so all of his joints are complex, single axis, rotational, and so we built a complicated hierarchy of jointing and rigging for his body. That was somewhat automated so that everything would properly move and bend by the animators. When we did finally get Sharlto’s performance we would properly match that.”
Although Image Engine considered performance capturing Copley, it proved the wrong fit for Blomkamp. “Sharlto is in all the plate photography with the other actors; then we removed him and replaced him with the digital Chappie,” Harvey continued. “The animators basically just had him in the background and fully hand key-framed on top of it to match his performance. The other thing we did was use it as an incredibly accurate lighting reference by sticking the same gray material in the computer as a calibration to make sure that the lighting we put on our digital Chappie really matched what was on set.”
In terms of the “Real Gangsta” scene, it’s the transitional moment in which Chappie starts to fit in with his new “family,” a couple of desperate thugs played by Ninja and Yolandi Visser from the South African rap-rock group Die Antwoord.
“He’s young, he’s curious and doesn’t understand the world yet,” Harvey said. “He’s jumpy about things. But as he progresses he learns. By the time we get to the ‘Gangster’ scene, he wants to be one of the gang. And Ninja teaches him how to be cool and so Chappie starts to pick up different mannerisms… the gangster walk and some of the arm movements and head twitches. At the same time, you see him fighting with good and evil when he’s taught to use a gun and says he can’t do that.
“We also got a great body performance from Sharlto. He did a number of things to help his performance and asked to put on these shorts and we stitched them on so he could get that gangster gait. He really understood it was going to be a team effort and even visited the facility and talked with the animators, so he was very aware of the work that didn’t come until afterwards. He was also asking if his performance was too much or too little. We also enhanced some of Sharlto’s head performance, exaggerating twitches and other movements to get a better emotional read.”
But there was also a lot of cartoony popping, snapping and twitching — and those ears are very exaggerated. It’s all part of what makes Chappie funny, compassionate and endearing — the conscience of a new humanity.