Animation supervisor Kenn MacDonald explained that Zemeckis used motion capture because "Even though it feels like live action, there were a lot of shots where Bob cut loose. Amazing shots. Impossible with live-action actors. This method of filmmaking gives him freedom and complete control. He doesn't have to worry about lighting. The actors don't have to hit marks. They don't have to know where the camera is. It's pure performance." A 25 × 35-foot stage was built, and it used 244 Vicon MX40 cameras. Actors on set wore seventy eight body markers. The cameras recorded real-time footage of the performances, shots which Zemeckis reviewed. The director then used a virtual camera to choose camera angles from the footage which was edited together. Two teams of animators worked on the film, with one group working on replicating the facial performances, the other working on body movement. The animators said they worked very closely on replicating the human characters, but the character of Grendel had to be almost reworked, because he is a monster, not human.