The installations are part of Mr. Ai’s effort to draw attention to the international refugee crisis, the subject of his new documentary, “Human Flow,” which opens in New York and Washington, D.C., on Oct. 13, and represents a year and a half of work, during which he traveled to a dozen countries.

“It’s really one project,” he said over a hamburger dinner on Houston Street. He is something of a refugee himself: He was stripped of his passport and detained in China by the Chinese government for more than four years, from 2011 to 2015.

Some 65 million people around the world, he says, have been forced from their homes by conflict and persecution — the greatest displacement since World War II. “This is not just a regional crisis,” he added. “It’s global, it’s historical. The numbers will get bigger.”

Mr. Ai is also giving public talks across the city on the topic. “I don’t know who would do this, five talks in 10 days,” Mr. Ai said of his commitment to the cause. Only him, was the implied answer.