Refugees walking near the camp at Idomeni, on Greece’s northern border with Macedonia, in a scene from the documentary. (Amazon Studios/Participant Media)

The Chinese contemporary visual artist Ai Weiwei — whose portraits of political dissidents, formed from Lego blocks, are on view at the Hirshhorn Museum and Sculpture Garden in Washington — has never limited himself to a single medium. Over his career, the 60-year-old has produced powerful sculptures, installations, photographs, videos, even a stream of social-media postings that can be read as both a form of performance art and as political statement. Ai’s heartbreaking new documentary, “Human Flow,” about the global refugee crisis, continues a tradition of making work that is pungent conceptually and aesthetically. (The movie is distributed by Amazon Studios. Amazon chief executive Jeffrey P. Bezos owns The Washington Post.)

Shot in 23 countries and culled from 900 hours of footage of refugees from the Middle East, Africa, Mexico and other places, the film largely avoids the tropes of standard documentaries, using on-screen facts and figures only sparingly or in the margins, and narration not at all. “News crawls,” featuring headlines from PBS, the New York Times and other journalism outlets, regularly creep across the screen, adding minimal context, and contrasting sharply with fragments of poetry. If at times it is not immediately clear which of the 40 refugee encampments Ai visited we are looking at — Greece? Kenya? Italy? The West Bank? — or who is on-screen, that’s part of his point.

In place of talking-head interviews that might lend clarity, Ai’s signature shot seems to be the overhead drone sequence, offering breathtaking bird’s-eye views of, say, a refugee-packed boat on the open sea or an expanse of cubicle-like shelters inside a massive airplane hangar. Aestheticizing the tragic does not undercut it, but reinforces it.

In other scenes, Ai simply turns his unblinking camera on an individual — who may or may not speak — forcing the audience to confront, over an uncomfortably long time, the common humanity we share with those who are, all too often, rendered as statistics. At nearly 2½ hours, the film is long, and it sags here and there, but the cumulative effect is not exhaustion or boredom, but rather sorrow and outrage at the violence, economic despair and persecution — whether religious, ethnic or political — that have driven these people from their homes.

At a couple of points, Ai turns his gaze from the flow of humanity to focus on an animal. One wordless sequence features a cow limping unsteadily down an unidentified street. Another segment details the herculean effort and expense undertaken, in 2016, to relocate a single tiger from a zoo in Gaza to the South African wild. At these times, by deliberately playing on our sympathy for nonhuman suffering, “Human Flow” asks us, implicitly, why we seem to care so much about certain living creatures and not others.

PG-13. At Landmark’s E Street Cinema. Contains disturbing images and themes. 145 minutes.