What a VFX Chrome Ball Does on Set

A chrome ball records the environment around the subject so CG elements can be lit from the same light as the plate. Here is what it is and how it is used.

Two names for the same job

A chrome ball is also called a chrome sphere, a mirror ball or a reflector. Whatever it is called, it does one thing: it collects the environment around the subject into a single reflective surface the camera can record.

Why the reflection matters

Everything that lights the actor also lights the ball. When the ball is polished well enough, that reflection can be turned into a lighting environment in post production, so a CG element is lit by the same sources as the plate.

Why polish quality decides the result

A sphere that is not finished properly bends the reflection. Our spheres pass more than 20 surface processes to maintain specular reflection, because any distortion in the mirror becomes a distortion in the lighting.

What to shoot with it

A chrome ball is only half the reference. The grey ball gives the exposure anchor, and a colour check chart gives the grade a neutral start. Most crews shoot all three in the same position.