From The New York Times obituary of Bobbi Ercoline (March 27, 2023):

The photographer who happened upon the group was Burk Uzzle, freelancing for the Magnum agency. He had visited the concert stage but decided that the story was elsewhere — the hundreds of thousands of audience members, some tripping, others building tents, skinny-dipping in a pond and sharing crates of bananas and loaves of bread.

Mr. Uzzle woke up at about 4:30 on Sunday morning and roved through the crowd. He spotted Bobbi and Nick and made use of advice from the Magnum founder Henri Cartier-Bresson, who had told him to study the detailed compositions of the Quattrocento painters of Renaissance Italy, as Mr. Uzzle told The New York Times in 2019.

"I walk up and I know the curvature of the hill has to work with the curvature of the heads," he recalled. "And there's the flag, it's going to have to be there, and just enough of the people."