PHOENIX — It was about 6:30 a.m. when the saguaro fell and the group chat lit up.
Lidar scanners — the same tech that allows self-driving cars to create 3D maps of their environments — had been capturing the day-by-day evolution of the giant cactus for six months. They recorded the colossus as it pulsed with life, eventually tilted and ultimately toppled in the vast Sonoran Desert of Arizona in February 2024.
That WhatsApp chat was filled with researchers, technicians and artists who had been scanning the plant as part of a yearslong art and data project, said Laura Spalding Best, the senior director of exhibits at the Desert Botanical Garden in Phoenix, which commissioned the project.
"It was so emotional and meaningful for everybody. [There] was like an excitement. But it was also super sorrowful at the same time," said Best. "And that's kind of what ends up being encapsulated in this video. You see that it's deteriorating, but it's still giving life to everything around it in this environment."
The video Best describes is part of a new art exhibition at the garden called "Framerate: Desert Pulse," a collaboration with the technologically savvy artist group ScanLAB Projects based in London. It's made up of detailed 3D scans of Arizona's unique desert landscape featuring iconic saguaro and other cacti, such as prickly pear, ocotillo and cholla — also known as a "jumping cactus" for its pads' uncanny ability to cling to passersby.
But it also chronicled a housing development sprouting on the edge of the desert, a dairy farm crowded with cattle and Chase Field crowded with baseball fans on opening day for the Arizona Diamondbacks.
"You have things like a Target [parking lot] and the landfill site, which hopefully question some of the slightly less sustainable things that we do as a species," said Matthew Shaw co-founder of ScanLAB Projects.
The imagery of the desert plants is projected on a loop on giant screens placed outside among plants in the garden. It's also featured in a room with screens on the walls, floor and ceiling, immersing people in the art. The video is backed by a booming soundtrack, composed by Pascal Wyse, largely using materials found in the desert such as saguaro spines. The effect is meant to be a celebration of the Sonoran Desert, as well as a cautionary tale about humans' impact on it, said Shaw.
The science in the art
Those 3D images are captured over time with scanners that fire millions of laser pulses into the landscape.
"They reflect off every surface that they come into contact with and they create a perfect 3D model of the space," said Shaw. The technicians repeated that process every day for a year.
The scans captured cactuses expanding as they absorbed water and reaching their arms higher into the sky. They documented the desert sands shifted by humans and animals. Pebbles twitched, branches waggled, cholla wiggled, weeds erupted then dried up and died.
"I think we could never have imagined [the desert] would teem with as much life as we found it to," said Shaw.
Those lidar scans created billions of data points — they call it "digital dust" — that can be used by the garden's scientists for their conservation work.
"Because of the nature of this being data-driven artwork and we're a data-driven institution, we now have incredible records of growth that you would never get from going on to the same field site every day," said Best.
What can come from this information?
"In some ways, it's bound only by our imagination," said Kim McCue, vice president and chief research officer at the garden.
Already McCue has observed an agave, a rosette shape succulent, folding and unfolding its leaves over the course of days.
"(We had) no idea that agaves would be doing that," said McCue.
"The question is, is there an adaptive purpose to this? By opening and closing the rosette, the leaves of the agave, is it protecting them from heat?" she added.
Ultimately, this data could lead to better conservation efforts — but it will likely take years to dig through the gobs of information.
There is precedent for this: Previous artwork by ScanLAB studios has been used to produce a scientific paper about coastal erosion in England, information that can be used to improve protection of coastal infrastructure.
That fallen saguaro was a seminal moment for those involved in the project. After it toppled, the lasers captured the fallen cactus over the next six months as it nourished the surrounding wildlife and then shriveled back up into the desert landscape.
"One thing that's interesting about the laser is the way it reflects off surfaces can represent … the amount of water that's under the skin and things like that. So that could be really, really fascinating when it comes to this saguaro," said Shaw.
Those scans could provide valuable information to scientists trying to understand why the giants succumb to the desert — and how to protect them.
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