Billie Eilish transformed into a cartoon character for animated segments

Billie Eilish stunned fans as she wore a motion capture suit in a behind-the-scenes video from highly anticipated concert film 'Happier than Ever: A Love Letter to Los Angeles.'

The seven-time Grammy Award winner mesmerised her admirers as she agave them a behind-the-scenes look at how her animated alter-ego was created.

The music icon shared a video to her Instagram Story in which she can be seen sporting a red and black motion capture suit covered with reflective markers.

Eilish captioned the pic: 'shooting the motion picture for the animation in "a love letter to LA" craaaaaaazyy.' she added several swirly eyes emojis.

The singer also put on a large black mocap helmet. Motion caption dots and lines were painted on her face and white balls were adhered to her hands, legs and shoes.

Billie Eilish, in 'Happier Than Ever: A Love Letter To Los Angeles', performs her entire new album on stage at the Hollywood Bowl. The live action scenes from the concert are intercut with animated segments in which Billie's character drives a car around Los Angeles.