Photo: TriStar Pictures

When director James Cameron was concocting 1991’s Terminator 2: Judgment Day, he knew that he needed its villain to evolve beyond Terminator’s formidable T-800, played — in both the original and the sequel — by Arnold Schwarzenegger. Enter the crew at George Lucas’s visual-effects studio Industrial Light & Magic (ILM), who were ready to deploy sophisticated computer-generated imagery and create the “liquid-metal” assassin T-1000.

Nearly a quarter-century later, in Terminator Genisys, which hits theaters July 1, the T-1000, played in T2 by Robert Patrick and now by Byung-hun Lee, will make its triumphant morphing return, but there’s nothing quite like the first time. Here, some of T2’s key visual-effects gurus, producers, and actors tell us how the most indelible aspect of this most memorable killer robot came to life.

For 1989’s The Abyss, Cameron and ILM made their initial breakthrough with a malleable CGI character that could take on human dimension — that film’s so-called “pseudopod,” or “water snake.” That creature contained the DNA of the T-1000.

Gene Warren Jr. (effects supervisor, Terminator, The Abyss, Terminator 2): The Abyss is where [Cameron] first tried out this notion of having a digital-animated creature. The quality of it even then wasn’t as good as it was in T2. The digital work was composited into the real backgrounds optically. If they tried to put out the film digitally, it would have made you throw up. They hadn’t yet made the resolution good enough. Cameron picked that water monster and decided to have ILM do it because it was gonna be translucent. And because of the contrast in water, it has a particular look; it’s a unique thing, just like lightning, just like fire.

Dennis Muren (visual-effects supervisor, ILM, The Abyss, Terminator 2): If you look at it and imagine what the water snake would be, it’s an inverted, upside-down image that you’re looking through and is distorted, and you’ve got a reflective image off the surface of it. That’s what it looks like looking through water, so we could always make that distortion work if we ran into problems.

Warren Jr.: Cameron thought he’d get away with the pseudopod, and it worked. Then he took it a step further with T2 and the liquid-metal man, and chose mercury as what it was gonna look like; because the only thing for which the digital would be real-looking enough was mercury, because mercury doesn’t look real in real life. It balls up, it reflects everything — it looks like a digital-created thing.

Rebecca Keegan (author, The Futurist: The Life and Films of James Cameron): He actually had the T-1000 written in the first Terminator movie, but neither the technology nor the budget of the era would allow him to do it, so he cut it out of that story. Even way back when, it was going to be this big, lunky T-800 and this cool, liquid-metal T-1000.

Despite Cameron’s status following the hits Terminator and Aliens, finding financing to execute his elaborate vision for T2 was trying, and contributed to the seven-year lag between the original and the sequel. But the ILM crew also needed time to hone their technical capabilities.

Mario Kassar (producer): When I went to see the premiere of The Terminator, I was fascinated by it, and I told James, “My God. Any time you have something else, please come to me.” Cameron and I had lunch, and he told me the story [of T2] and I said, “Okay, go write it and we’ll make it.”

Muren: After The Abyss, I decided to take a year off and really understand CG. I got this big textbook and spent many months reading it in a coffee shop and came away realizing I don’t really know how to do this, and I don’t need to because we’ve got guys in the company who know how to make this stuff happen. But they need somebody to say, “This looks real and this doesn’t.”

Kassar: Cameron would say, “This is going to be an expensive movie because I’m gonna do so many amazing effects you’ve never seen before. In fact, let me go spend the money and show you how it will look.” James made a whole presentation of the effects in the movie. All that you see that was so advanced was done before the movie was shot. I think [it cost] close to $15 or $17 million to do those effects that were done before the shooting of the movie. When you saw the way he was gonna do it, you fell from your chair.

Muren: Jim had seen enough to know computers could do chrome-looking things. But whether or not you could make it into a shape and have it look like it has weight and [can] walk and change shapes, and put it into a background plate seamlessly, he had no clue if we could do that. I felt pretty confident we could. I got on a plane and flew to meet him, and Jim had a lot of storyboards laid out, and it just seemed wild and crazy and time to do it.

Keegan: People talk a lot about ILM, but actually, [special makeup producer] Stan Winston played a huge role. A lot of the shots people think are digital are not, including the, “Hasta la vista, baby” shot where the guy shatters. That’s a Stan Winston model.

Warren Jr: The techniques used in making T-2 were all over the map. There are things in there that are 100-year-old techniques that work to this day.

Jenette Goldstein (actress, Janelle Voight, John’s foster mother): The script kind of said, “She transforms,” or something like that, but it didn’t say anything about liquid metal. It didn’t describe anything about the actual process. It must have said, “Arm turns into a blade and stabs,” but it didn’t get explained to me what it was actually going to look like until I was on set. Even when it was explained to me, it was hard to imagine because it’d never been done before. I was surprised as anyone when I saw it.

Muren: Goldstein’s scene was the first thing we shot, and I didn’t know Jim’s temperament on it. We finished the part with her, and then I needed to shoot these empty backgrounds, which was funny because it was just the guy dead on the floor by the refrigerator. I said, “Jim, I can get this if you want to do something else.” Everybody just laughed at the suggestion. First of all, you don’t tell Jim what to do, but you don’t even try to help him. So he stayed there while we shot this background plate with nothing moving at all, because that’s his protocol.

Kassar: Cameron just went into his cave of CGI, genius, high-tech world with his own people and came back with all the scenes you would see in the movie, how they’d be integrated.

Muren: My goal was to teach Jim how to do this. So I made sure he saw how we gave the chrome look to the T-1000 and how I’d modify the reflections to make the thing look heavier. It really helped him understand the limitations and advantages of CGI. Jim is an effects guy, but this was unchartered territory. You can’t go in and do a free-for-all on something so difficult, and I was pretty clear on what the constraints were, and he was great at following them. He didn’t want to jeopardize the movie.

Goldstein: The way Robert Patrick and I worked on our roles is that went over to his apartment and he showed me his physicality. He talked to me about seeing the T-1000 as a praying mantis. He showed me how he was using his body with his head tilted forward and the ears being the focus of the movement, so that’s what I adopted when I became the T-1000. That’s why it works when I morph into him.

Kassar: Robert Patrick did a great job. The way he was moving and running and doing his thing made the T-1000 more real than the special effects.

Muren: That’s what happens when you get good actors and a good director. Robert had thought about the role, and it showed up in the work.

Released on July 3, 1991, T2 earned a then-staggering $54 million over its opening weekend and instantly set a precedent for integration of CGI in films, in addition to garnering four Academy Awards for its effects, makeup, and sound design. Although, if you ask the crew, nothing’s perfect.

Kassar: I think T2 broke the barrier of this effects thing. Okay, Star Wars was great, but what Cameron made was something quite amazing, and it’s because of his vision and the high-tech evolution he started.

Goldstein: Just as an audience member, it was fantastic. As an actor, I’m really glad I was able to sell it and have other people believe what was going on, but obviously, it was much better to see what I was imagining. All the effects were just incredible.

Keegan: Of course, the CG is groundbreaking and remarkable, but it’s the whole package that sells it. The CG artists’ work integrated seamlessly with the practical effects.

Warren Jr.: Right at the end, when the [T-1000] is flopping around, it looks a little cartoony. Jim knows it, but they couldn’t do it any better. He made the decision to go that route. It got down to when it was no longer putting that surface over real human beings — that’s when it rarely looks real, no matter how good you are.

Muren: That shot was the last thing we had to do, and we had computers at Cal-Tech, at Silicon Valley, every place we could find working to get that shot, and we just ran out of time. Every cheat I could think of we put in that shot. It’s nice and it wraps the story up, but that’s the only shot I wish we had a little more time on. It could have been even creepier.

Keegan: Ironically, the fact that they only had a budget to have a set number of visual-effects shots forced them to be more artful. I think now there are a lot of filmmakers who have a release date barreling down on them, a visual-effects budget, and story comes way down the line.

Kassar: You know T-800’s a robot, but he’s got humanity and a soul. At the end of the movie, Schwarzenegger’s going to go down into the fire and be melted, and there’s a tear that comes down. That tear says everything. If you’re a robot made out of this and that, you don’t cry, you have no feeling.

Muren: I’ve seen a lot of chrome things that have been done in films since then. Everybody is not doing it the way that I did it, and I think it’s hurting it, and nobody seems to care or notice. When Jim said, “I want this to be 100 percent reflective, it’s perfect metal,” I knew he didn’t mean that, because nothing in the world was 100 percent. And being a movie, you’ve gotta be able to relate to it.

Warren Jr.: The computer is another tool, and in the end, it’s how you use a tool, particularly when it comes to artistic choices. What the computer did, just like what’s happened all through our industry, it has de-skilled most of the folks that now work in visual effects in the computer world. That’s why half of the movies you watch, these big ones that are effects-driven, look like cartoons.

Keegan: The visual effects are what was groundbreaking about T2, but the storytelling around it was very good, and that’s why we’re still watching the movie.

Kassar: Everything that was done in that movie was so ahead of its time that even if you play it today against all those science-fiction movies or whatever you want to call them, it still stands as one of the best. It’s amazing.