The 65-year-old Chinese American director says it took two years of hard work by hundreds of people to create the character, which "cost two or three times" more than Smith, the actual actor.

Lee is determined to use technology to push new boundaries in filmmaking.

His Oscar-winning film Life of Pi featured a CGI tiger, inspiring him to create a human CGI character, which is more complicated.

Smith has stayed in shape throughout his two-decade career. But people change in subtle ways over time, from how they walk to their facial muscles, Lee says.

Lee studied many photographs and videos of Smith. He blew up the images by 6,000 times to observe the minute details of his appearance.