Projected onto a special kind of screen (usually the type called DILAD) using a 3D model rendered into 2D. The dancing would have been motion-captured (MoCap) from a professional dancer and applied to the model of Luo TianYi.
Thank you Mr John Ward for your reply. I am afraid your explanation has gone pass above my head. Are you able to elaborate much better for me. I am so curious. Thank you.