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Trixter Enters Age of Ultron for 'The Avengers'

VFX supervisor Alessandro Cioffi and animation supervisor Simone Kraus of Trixter Studios discuss their work for Marvel's super powered ‘Avengers: Age of Ultron.'

There’s nothing harder in Hollywood than trying to make a strong sequel to a successful superhero film. Fans come into the theatres with high expectations, meaning visual effects houses have to push the envelope and deliver the unexpected. For Avengers: Age of Ultron, that meant helping James Spader step into the metal skeleton of a legendary villain, redesigning Quicksilver’s abilities for a new franchise and creating a horde of robots capable of posing a threat to Marvel’s mightiest.  These tasks fell to the team at Munich’s Trixter Studios, and as VFX supervisor Alessandro Cioffi and animation supervisor (and Trixter Co-founder) Simone Kraus explain, it was a challenge the company enjoyed.

James Gartler: Your crew was relatively small on this project, correct?

Alessandro Cioffi: Yes, that’s correct. We’re not one of the big VFX monsters on the scene. We are what I call a visual effects boutique. We’re 80 in terms of crew plus some overhead production and pipeline, so it was around a 100 people, more or less. Trixter is a company that is growing and this project was a very important milestone in our growth process.

JGWhat’s it like working with Joss Whedon, who is so respected in this industry?

AC: He was great. As you’ve said, he’s multi-talented. He’s a writer, a director and a person with very clear ideas and a vision, which is important.

Simone Kraus: It was really fun working with Joss. He’s a super dedicated guy, fun and very calm when it gets busy.

JG: Trixter handled all of the ‘Party Fight’ sequence in the movie. What did that entail?

AC: It’s a very long sequence of almost 150 shots that happens at the beginning of the movie.  It’s particularly important because it’s the first time we see Ultron, who presents himself during this sequence, as Ultron Mark 1.  We worked on the entire sequence from A to Z here and developed both Ultron and the Legionnaires.  The whole fight is very intense and it traveled from department to department here and that gave us an opportunity to develop a very efficient workflow.

JGAction scenes often require the creation of digital doubles. Did you end up sharing your assets with some of the other VFX houses working on the picture?

AC: We do share assets, but the Ultron Mark 1 only exists in the sequence we worked on, so there was no real need to share it with other vendors. There were other digital doubles we actually did share. Some were built here at Trixter and delivered to all the others, and some made the opposite journey. In the Party Fight there are bits and pieces of digital doubles, like some head replacement here and there, but of the main actors we only developed one single digital double and this is Pietro/Quicksilver. For production reasons it was not always possible to shoot a plate for him. It was much more convenient to create a digital replica of the actor and let it run for him.

JGThe actor who plays him in Age of Ultron, Aaron Taylor-Johnson, has said in interviews that an effort was made in this film to not rely too heavily on green screen to differentiate this Quicksilver from the one seen in X-Men: Days of Future Past

AC:  Most of the time, 95% of the cases, he was running onset. We used green screen in only a handful of shots, sometimes because the action was a little bit too complicated to redo onset and therefore it was done later in a green box or in studio, or just for other specific shot-related reasons.

This character was particularly important for us and we started doing some preparation work together with the overall VFX supervisor, Christopher Townsend, in late 2013. That was around the time when Chris made the decision to shoot him mostly onset because we created a technique to isolate Pietro and give him some speed effects almost in-camera. We mimicked a practical photographic look which was integrated with CG trails. Much of the final look is what we call the photographic trail, which is achieved by treating and augmenting the real plate. Almost every shot involving Pietro, regardless if he was in the foreground or background, was shot with high speed photography, from 72 to 120 frames per second, so that we had plenty of frames to use to recreate this big effect.

JGFan are excited to finally see Pietro’s sister, the Scarlet Witch, but her powers from the comics are rather difficult to visualize. How did you go about deciding the best way to depict her abilities?

AC:  Thank you for this question because it has been a key point. Joss Whedon wanted to be true to the comics and was very keen on having a subtle effect. Another important point for the briefing was that it had to be possible to perceive that these characters are siblings. The look of Quicksilver and his powers and the look of the magic that Wanda creates had to relate somehow…which was tricky because again, Joss didn’t want to have anything either too obvious or too trivial. He was looking for something elegant and at the same time very subtle but clear. There was a long period where many versions were developed and alternate possibilities were looked at. Wanda does many different things: she has telekinetic powers, she can read minds, she can create shields of power and she can deliver highly destructive bolts. All these powers had to have something in common of course but at the same time had to be kind of unique and linked to the Quicksilver trails.

JGHow do her powers manifest?

AC: In the movie, she learns how to benefit from her powers. In the beginning everything she does is very subtle and is not too obvious and then her power grows with the rage and disappointment of the character. Visually, I would describe it as pure energy sourcing out of her wrists and growing through the fingers. Scarlet Witch mind-controls people so it’s very faint energy that travels from her hands into people’s minds or sometimes she has more angry gestures and you see these raging bolts starting from her hands and destroying all she has around her.

JGI have to ask about Ultron’s swagger when he walks. Your team created some animation tests that inspired James Spader’s performance?

AC: This was an extremely rewarding phase that Simone can describe, since she was taking care of the prep work…

SK: We got an initial Ultron sketch from Marvel and we added in a tremendous amount of detail. The main silhouette was there but it hadn’t been decided yet which pieces Ultron uses to build himself. For example, his chest piece is from an Iron Legionnaire, a specific one we see in the movie.  So, we figured out the details and once we had the first version that could be animated, we handed our rig to the Imaginarium – Andy Serkis’ motion capture company. A stage at Shepperton Studios was changed into a motion capture space for five or six weeks and we had the Imaginarium team set up there to mo-cap all the shots for Avengers. It was easy to transport the director, actors and supervisors back and forth between the different stages on the lot, which was a real luxury. It’s unusual to have everything so close together.

We had done a few test animations showing some initial movements, so when I met James Spader together with Christopher Townsend for the first time, we thought it might be helpful to show James a few options of how that character could move, to break the ice and give him an idea of what we were talking about. From there, we started experimenting. 

First, he had to get used to the motion capture gear and seeing himself for the first time on a screen as Ultron, using a real time, low resolution CG avatar of the character. We played around with what his typical body language would be, his initial poses and the way he walked. James had some fantastic ideas: one was that his right arm wasn’t working properly, so we put it in a sling; another was that he could bend one side of the body a bit more than the other and drag one leg behind him, so we put him in several different restraining devices so that he didn’t have to think about it all the time and it became natural. We also asked him questions about how he sees the character and recorded the whole session to then be able to show to the animators later on.

The Ultron Mark 1 doesn’t have a face so we needed to come up with a specific body language expressive enough to translate the character of James Spader behind it. I think you really see it even though there isn’t any face to look at.

For the capture process, we also had people from editorial there so that we could see the scenes in context and also be able to put them through the pipeline knowing which takes were the favorites. It was a very efficient process for handling the data and workflow. We were able to use the mocap data in almost every shot. We had a few shots where we had to keyframe the character but we knew the specifics of how James saw things, which was really important.  Obviously, when a director is casting an actor like James Spader, who is a fantastic actor – I was very impressed by him – it was our first goal to make it clear that it is him in there.

JG: So Spader did all of the motion capture work for Ultron?

SK: …almost all of it for Ultron Mark 1 and then also later on for Ultron Prime, which was ILM’s work.

Avengers: Age of Ultron is in theatres now.  For more information on Trixter, visit


James Gartler is a Canadian writer with a serious passion for animation in all its forms. His work has appeared in the pages of Sci Fi Magazine, and at the websites and