Reducing the weight of this structure to allow it to unfold easily posed a challenge to scientific experts, who carried out numerous experiments to find the right materials to produce the "ice rings".

"Raising the ice square (which was later sculpted into ice rings) was extremely complicated and involved lots of technology," Chang said.

He added that he had discussions with director Zhang about the concept for Friday's ceremony.

Chang said the opening ceremony for the 2008 Summer Olympics told a good story about China's past, while the Winter Games presented a story for the future.

"It's about how Chinese people see the world, including how we should make efforts toward a shared future," he said.

Zhang repeated the word "relaxed" several times when talking about his preparations for the ceremony.

"I feel really relaxed this time because of my confidence in our culture and civilization. The whole team also feels this confidence," he said.