Margot Robbie‘s ice skating in I, Tonya wasn’t all computer wizardry, as shown in a new visual effects breakdown video from Eight VFX, but a lot of computer magic went into transforming the Oscar nominee into controversial skater Tonya Harding.

“We had Margot, which was amazing. She was so diligent, and she trained five days a week for five months and her, with a skating coach, figured out how much they could do — and I was amazed,” director Craig Gillespie says. “She’d go out and she’d do 30, 40 seconds of it, and I was kind of astounded she could pull it off.”

For everything else, Robbie had two stunt doubles, choreographer Sarah Kawahara relayed to IndieWire. As shown in the video, 3-D head scans were taken of Robbie, which were then superimposed on her doubles’ faces when they skated close to the camera.

For those interested in the technical aspects of filmmaking, the VFX developers explain how six witness cameras were set up around the ice rink and synched to the time code of the 35mm camera that circled Robbie. This, says VFX producer Juiet Tierney, “allowed us to have an accurate position of Margot Robbie in every shot in each stadium.”

Since its debut, I, Tonya has been nominated for three Oscars — Best Actress (Robbie), Best Supporting Actress (Allison Janney), and Film Editing. Janney also took home a Golden Globe for her performance.

Watch the VFX magic of I, Tonya in the clip above.

I Tonya
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