How UNIT created a CG photoreal gorilla for Paramount+ drama Stags

UNIT VFX supervisor Nuno Pereira tells TVBEurope about the work that went into creating an emotive CG gorilla called El Ni o

By Jenny Priestley

Published: January 14, 2025

UNIT VFX supervisor Nuno Pereira tells TVBEurope about the work that went into creating an emotive CG gorilla called El Ni o

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Released by Paramount , Stags follows Stu, who heads to South America for his stag do with a group of his closest friends. But what they expect to be a fun-filled week takes a dark turn with the group sent to a lawless prison island run by two warring siblings.

Production company Eleven Film called on UNIT Film & TV to create El Ni o, a CG photoreal gorilla as well as CG environments for the series.

The producers wanted UNIT to enhance the live-action suit version of the gorilla that was used on set, VFX supervisor Nuno Pereira tells TVBEurope. We built a really strong team around the challenge and ended up creating a full CG asset which was used in most shots. In the end, together with Giancarlo Sanchez, the director, we felt this was necessary to bring a crucial character to life, which was vital to the visual storytelling.

El Ni o Pereira led the UNIT team which brought to life the gorilla's movements, fur, eyes and overall emotive performance.

Our team focused on achieving a photoreal and naturalistic look for El Nino, which involved incredibly detailed animation and accurate lighting, he continues. We aimed to ensure the creature felt integral to the story, blending seamlessly with the live-action elements and enhancing the overall tension and drama of the series. As we started to develop this asset, and we were having rounds of feedback and dailies with the client, everyone realised that with so much work put into this asset to only have four shots, it would be a waste not to do more. So the shots and sequences, which included the CG version of the gorilla, quickly grew in number, scope and ambition.

The team carried out intensive background research work for both the look and development of the creature as well as its behaviour. Alongside many other sources of reference, we went to the extent of contacting a zoo to allow us to capture these amazing creatures in the closest way possible.

Creating realistic fur on screen can be notoriously difficult, traditionally the team at UNIT would use Houdini's fur tools but for Stags creature supervisor Aritz Basauri opted to use Maya and Yeti. Though we still did all the dynamics in Houdini, we had to develop proprietary tools and come up with a specific pipeline to manage the data back and forth between the applications without losing any detail, explains Pereira.

Another tricky part of the project was getting the gorilla to emote. After capturing the gorilla suit performance on set, the team felt it didn't provide enough range of motion and the performance wasn't quite right .

When you get that close, it's just not a real animal. The gorilla emotes only through its body language. But there's a really good mix of in-camera gorilla with full CG.

Our animation supervisor, Brett Margules, did an outstanding job in creating the baseline actions for walking, breathing, running and the facial expressions that were all very much grounded in real life gorillas. The animations for most shots then stemmed from that. We worked very closely for several weeks with the rigging team to ensure we had ample control over what we could do with the gorilla. However, we always kept true to what the real animal can do and made the conscientious decision to stick to that so we didn't create something that started to look unrealistic or like a movie character.

Pereira says it was important to create small, intricate details to help build realism, such as when the gorilla's hands land on the floor creating dust motes and changing the way his fur moves.

We go from the start where we experience the creature as a terrifying, brute force of nature and by the end of the sequence, people realise there is another side of El Ni o, and we only had 3 or 4 shots to make that happen, he adds. El Ni o realises that Gaucho is wounded and reaches out for the wound and then, really tenderly to him. This was the key moment where the gorilla connects with Gaucho and where the practical suit did not have enough range of motion to portray what the real gorilla does.

When we were on set, Javier, who plays Gaucho, started ad-libbing so all of these gestures that he's doing - none of those were scripted. Giancarlo and myself thought it was gold, and we could do a lot with it and that it could help inform the animation and the performance of the gorilla. So when Gaucho does something with his mouth, we have the gorilla mimicking him. This connection was really, really hard to achieve the look in the gorilla's eyes, as you were cutting directly to a human. It's really hard to just cut back-to-back sequences where you have real human emotion and then digital pixels.

In total the UNIT team worked on Stags for a total of 17 weeks, delivering both El Ni o and other visual effects across the series. In the end, from those initial four shots, the UNIT team delivered over 300 VFX shots across three episodes, states Pereira.

LINK:	https://www.tvbeurope.com/production-post/how-unit-created-a-cg-photor...
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