Most aspects of the Olympic opening ceremony remain closely guarded secrets but a few tantalizing details have emerged about the Aug. 8 extravaganza orchestrated by award-winning film Chinese director Zhang Yimou.

The opening and closing ceremonies in Beijing promise to be two of the most spectacular events ever seen, with fire, water, light and music likely to enhance the traditional Chinese themes.

At a dress rehearsal July 11, the whole "Bird’s Nest" stadium was lit up to resemble a giant cauldron for the Olympic flame, with pink, white, orange and red fireworks shooting up into the night sky.

"During the climax of the performances, we will display the thousands of pictures of smiling faces collected from all around the world," said Cai Guoqiang, the renowned artist who is directing the visual and special effects for the opening and closing ceremonies. "At that moment, to accompany the picture display, we’re going to release the fireworks depicting 2,008 smiling faces in the sky."

Cao said the projection of the 2,008 firework faces was "technically very demanding" and had taken two years to perfect.

He gave away a few more details, saying that red peonies and a yellow firework-dragon spanning up to three kilometres will spring up around the edge of the dragon-effect lakes of the Olympic Green immediately after the Olympic flag-raising.

Cao’s website describes his artistic approach as drawing on a "wide variety of symbols, narratives, traditions and materials such as feng shui, Chinese medicine, dragons, roller coasters, computers, vending machines and gunpowder."

Some 35,000 fireworks at the opening ceremony will last a total of about 20 minutes and will include the first aerial display of the five Olympic rings, said Wang Ning, the deputy director of the opening and closing ceremonies.

Wang and Cao said more fireworks will be set off in nearby areas including the Olympic Forest Park, along a central axis leading from southern Beijing through Tiananmen Square to the Bird’s Nest, and on the Juyongguan section of the Great Wall close to Beijing.

Zhang Yimou said recently his crew was working at night to get used to the evening performance of the opening ceremony, which is scheduled to begin at 8 p.m. on Aug. 8.

Musical director Chen Qigang told the official China Daily that he planned to accompany the performances with music reflecting an "impressive combination of Chinese classic, contemporary, highbrow and pop elements."

Chen said he had tried to find subtle ways to "display such unique Chinese culture" as Kunqu Opera, Peking Opera, and ancient musical instruments.

"But it does not mean we would put on Peking Opera plays, or bring out any particular Chinese traditional instrument," he told the newspaper.

State broadcaster China Central Television said armed police maintained strict security in three concentric cordons around the stadium before and during the rehearsal.

All stadium workers and gardeners on the site reportedly signed confidentiality agreements with the organizers, but many rumours circulated before and following the event. More concrete clues emerged through photographs of the dress rehearsal posted on the internet.

Many performers were photographed wearing ancient costumes, including some sporting military attire similar to the famous Terracotta Warriors, which were excavated from an imperial tomb near the former inland capital of Xian.

Other performers wore dark suits covered in small light bulbs, and one group carried a giant cut-out wooden puppet.

Zhang is expected to feature all 56 ethnic minorities officially recognized as part of the People’s Republic of China.