What does a visual effects supervisor do, exactly?

Matt Johnson (left) in Los Angeles on Beverly Hills Chihuahua

What does a Visual Effects Supervisor actually do – and how do you become one? Matt Johnson, veteran VFX supervisor on dozens of Hollywood hits, including World War Z, Into The Woods, V for Vendetta, X Men, and Chronicles of Narnia, explains what a Visual Effects Supervisor actually does for a living, and how an aspiring film-maker might become one.