Aster said it was a “long process of trial and error” to find the exact nuance of the visuals. “There are some things we did in camera, but for the most part we had visual effect artists doing that in post,” he said. “I’m sure for some of those shots we got to the point where we had 60 versions. In one iteration the tripping was way too distracting and you're not paying attention to the characters, and then you brought it down to the point where if you are paying attention to the characters, you'll never notice the tripping effects.

Source: Los Angeles Times July 04, 2019 01:47 UTC