Oscar-winning director Ang Lee wanted to explore Indian culture while shooting for his much awaited movie "Life Of Pi" in the country. He says in the process he has discovered that Indian children have "the best smile" and are "always happy".

Based on Canadian author Yann Martel's Booker Prize winning novel "Life of Pi", the 3D fantasy adventure film follows the journey of an Indian boy from Pondicherry who survives 227 days after a shipwreck while stranded on a boat in the Pacific Ocean with a tiger.

"I have a lot of Indian filmmaker friends and it was great shooting here in India. I had to shoot here for a specific reason as I had to research about the culture, visit temples. Basically, I explored the culture of South India," Lee told reporters here Monday.

"One strange thing I have noticed is that the children here have the best smile. They are not shy, they are always happy," he added.

The filming of "Life Of Pi" began with a two-week shoot in India in March 2011. After 10 days in Pondicherry, Lee moved to Munnar, for further shoots.

"Life of Pi" will be released in English, Hindi, Tamil and Telugu Nov 21 and Lee describes it as his hardest film so far.

"I had a wonderful experience making the film. I was so anxious to bring this movie to you. It's the hardest movie that I have made so far. I gave my four years to the film. It will be a new theatrical experience. It was very stressful for past four years," Lee said.

He is starting the film's promotion from India and showed a 20-minute unseen exclusive footage to journos and well-known names from Bollywood - Anubhav Sinha, Amol Gupte, Kabir Khan and Kunal Deshmukh, among others.

One of the highlights of the film is the tiger called Richard Parker and it has some amazing scenes with young Pi, played by 19-year-old Delhi boy Suraj Sharma.

Lee thanked the animators for doing an outstanding job on the tiger.

"I didn't know whether it will work but I must say it is working. I have to compliment the animators for their great job."

Lee was joined by the important cast members, including Irrfan Khan, Tabu, and Suraj.