THR reported in 2016 ahead of filming that Alita was budgeted in the $175 million-$200 million range. The film has long been in development, with James Cameron attached to direct since the mid-2000s. So Rodriguez had big shoes to fill taking over for Cameron, who opted to focus on the sequels to 2009's Avatar.

"My job was to go make what he created come to life so that he wouldn't have to, because he was going to be busy with Avatar, because otherwise, we'd never see this movie,” Rodriguez said. “The last thing I wanted was him to watch it and go, ‘Uh, damn it, I knew I should have shot it myself.’ So I wanted him to feel like it was a Jim Cameron movie, too.”

Based on the Japanese cyberpunk manga created by Yukito Kishiro in the '90s, the character Alita and manga is a well-loved property. Once Rodriguez took over the script, it was a matter of finding the right person to play the right star.

“We saw hundreds of girls," he says of casting Rosa Salazar as Alita. "She was just the most emotive, the most captured. From the first time we saw her, I couldn't imagine anybody else.”

Salazar recalled her long audition process as being about emotion and heart.

"I'm a very emotive person, so I think that was part of the thing that clinched it for me," she said.

During a Fox showcase Friday evening, press and fans had an opportunity to see more than 20 minutes of the film via various clips with producer Jon Landau setting up the clips showing off Alita’s strong relationship with her pseudo-father figure, Dr. Dyson Ido (Christoph Waltz), and her advanced fighting skills. Salazar had to train hard due to her character being skilled in Panzer Kunst, an amalgamation of several different martial arts techniques.

“I did Eagle Claw, Muay Thai, kickboxing, staff work," she said. "It was a well-rounded body stuff we worked on for about five months, two and a half hours every day except for Sunday, and changed my diet and my life."

To get the look of the film right, Rodriguez and his team teamed with Weta Digital, known for work on the Lord of the Rings films, King Kong, The Jungle Book and Avatar. Rodriguez said the effects company continued to push itself with Alita, particularly the lead character's facial expressions.

“Even though they've done all those technological breakthroughs, we still have to keep adjusting and breaking the face," he said. "Every time they'd come up against a new scene where Rosa is very expressive, she does an expression that's not translating, they got to rebuild the face again and then change all the faces they did before to update them."

The film was recently pushed from December to Feb. 14, and Rodriguez hopes audiences will opt to see it on Imax in 3D.

"We shot it in native 3D. Jim [Cameron] and I had always been big 3D proponents," he said. "And because it's a true vision of the future. I mean, it's really so detailed and seen, heard, larger-than-life. I would want to see a Jim Cameron movie on the big screen. I saw Avatar on a huge Imax screen and that marked my life.”