The Internet is still reeling from the early release of Marvel's Avengers: Age of Ultron trailer, which promises to raise the stakes even higher from what Earth's Mightiest have faced in the past. At the center of it all is Ultron (James Spader), the self-aware A.I. who breaks free of his 'strings' and wrecks havoc on the planet. The trailer didn't show much of the villain in action, but the glimpses provided (and a killer one-liner) illustrate Ultron's potential to surpass fan-favorite Loki (Tom Hiddleston) when it comes to posing a super-powered challenge.

Spader has already discussed the psychology behind the character, but now we've learned more about the filmmaking process that it took to make Ultron a reality on screen. In an interview with Total Film, the actor detailed how the advances in motion-capture technology played a large role in putting the final product together:

"When you first meet Ultron, his physicality is very different to what he evolves to. It was in the script but we arrived at the metamorphosis of him on the set. In practice, in rehearsals... we were able to create the physicality of the character on the motion-capture stage. They would dot me up and I was wearing a helmet that had two cameras on my face, and they could live stream it to a monitor so we could try different things."

Avengers 2 Age Ultron Trailer Clips Agents of Shield

Spader mentioning the "physicality" and evolution of Ultron plays in line with what was shown in the teaser; that Ultron will continuously upgrade over the course of the sequel's runtime. When he makes his fateful first appearance at the party in Stark Tower, he looks like an old piece of scrap, walking in an almost zombie-like fashion (one might say, a puppet on a string). As the story progresses, Ultron becomes the fearsome being shown in the trailer's final shot, moving freely like an organic creature.

As such, it shouldn't come as a big surprise that Spader was required to experiment during his performance. The evildoer is going to appear in multiple incarnations during Age of Ultron, and in order to portray those accurately, it makes sense for the actor playing him to mix things up along the way, trying different things to see what works and what doesn't.

But Spader didn't just act alone on the mo-cap stage. One of the benefits of this technology is that it allows the thespians playing digital creations to interact with the physical aspects of the set, creating something that feels more fluid and realistic.

The Avengers 2: Ultron with Captain America and Iron Man

Like Andy Serkis before him, Spader was able to enjoy this luxury as well, acting out his scenes with his co-stars, which allowed director Joss Whedon to capture everything about Spader's performance - including his voice.

"I'd go and shoot the scene with the other actors and they're recording all of it, including my voice. Nine times out of 10 they were not using ADR (additional dialogue recording) after the fact."

This shouldn't just help Ultron be more believable when audiences see him on screen, it also most likely aided the ensemble of actors playing the Avengers to buy into what was happening as well. Instead of going against a tennis ball on a stick, the likes of Robert Downey, Jr. and Chris Evans were possibly able to give more natural reactions to the A.I.'s threats against humanity. That's a fact Andy Serkis has proven multiple times already, and a new element he brought to Mark Ruffalo's Hulk, as well.

Ultron's holding Earth

Ultron may be a psychopathic robot, but when a talented actor like Spader is in the mo-cap suit, it's no surprise the cast has uniformly credited him - not the digital artists - with granting Ultron his on-screen identity. Between Spader injecting Ultron with some personality and emotion and the ILM effects team translating that to the finished shots, it looks like audiences will be in for a treat when the highly-anticipated followup finally hits theaters next summer.

The Avengers: Age of Ultron debuts on May 1, 2015.

Follow Chris on Twitter @ChrisAgar90.

Source: Total Film (via ComicBookMovie)