They were testing the Perseverance Mars Lander's Vision System. I just learned this while trying to fall asleep watching my YouTube feed which includes a subscription to NASA's channel. I was enjoying this video prior to launching into dreamland when at 1:17 my eyes got big as I recognized a scene from DEVA and then two more scenes. Check them out here and see if you can ID them. Spoiler Alert: I've labeled the scenes below the link so don't peek or cheat before you view the video. 
https://youtu.be/dfveEbxxnzk

I am assuming NASA selected DEVA for two primary reasons. 

1. The terrain resembles that of Mars. Click here and at 24:00 you'll see how DEVA resembles the river beds, sand dunes, mountains, craters, and terrain of Mars.
https://www.youtube.com/watch?v=P-M1Jb7FlSg

2. DEVA is close to Pasadena, CA home of The Jet Propulsion Lab. 

I did some more digging on NASA DEVA testing of Perseverance and found these links if you have more interest. 

https://mars.nasa.gov/mars2020/multimedia/videos/?v=454
https://mars.nasa.gov/resources/22494/na...te=insight

Video Testing Scenes

1:17 Zabriskie Point
1:20-31 Death Valley Airport - Furnace Creek with The Panamint Mountains to the west and way off on the horizons the Funeral, Grapevine, and Cottonwood Mountains. 

I was working at JPL when the first Rover landed. Once the cameras were turned on, they looked around and took notes. Then they built 2 or 3 settings to mimic the landing area, right down to the color and size of the grain of the sand and rocks. Sun angle was also thrown in. They hand copycat machines they would practice the future movements of the machine, right down to the delay because of the distance for the signal. I will never forget those rooms and practicing done by one of the operators, he had the first man bun I had ever seen.

Hahaha, Sparky. "Yeah so I was at JPL, put the Rover on Mars, yadada, and I will never forget ... MAN BUN." Thanks for the laugh.

(2021-02-17, 07:19 AM)Sparky of SoCal Wrote: I was working at JPL when the first Rover landed. 

Wow, out of my respect for space workers I am honored to have you in this forum and grateful for sharing your experience at the JPL. 

I used to time my trips to DEVA to coincide with The Mars Fest which I enjoyed immensely sitting in the auditorium on the front row listening to the scientists and during the day visiting the displays under the canopies on the Visitor Center patio.

Hold your horses DVD! Thank goodness I am no rocket scientist. I simply helped design and build things to allow the contractors at JPL to do their job. Clean Rooms, Labs, test areas, stuff like that. I will not take a cut in pay to be labeled a Rocket Scientist.

(2021-02-18, 11:12 AM)Sparky of SoCal Wrote: I will not take a cut in pay to be labeled a Rocket Scientist.

Too funny. BTW the JPL tours are a hard ticket to come by. I tried to take my grandkids through two years ago and was unable to score tickets, even online in a timely manner. 
I type this as Perseverance is landing on Mars. Way cool!