Guardians of the Galaxy: The VFX Behind Knowhere Revealed

This feature first appeared on the Framestore blog.

British post-production house Framestore is the global leader in visual effects that recently hit the headlines for its Oscar-winning work on ‘Gravity’. In this blog from their company website, the firm explains how it brought Knowhere to life in Marvel’s ‘Guardians of the Galaxy’.

The Middle of Knowhere

Shrouded in vibrant nebula (a stylised combination of matte painting and FX), Knowhere is an entire city built inside the mined-out, severed head of a giant celestial being, three-miles wide and filled with massively detailed geometry.

Above: Approaching Knowhere In Marvel’s ‘Guardians of the Galaxy’

“I have a lot of favourite things about this show, but my heart belongs to the interior of Knowhere,” says VFX Supervisor Kyle McCulloch, “we just spent so much time developing it and making it a real place. We designed different neighbourhoods with different colours and different types of houses, there’s so much backstory that went into the design and making it complex enough to be real. In the end I hope it just goes by and provides a great visual backdrop, but for us there was so much that went into making it.”

Above: Some of Framestore’s concept art for Knowhere

Work on Knowhere started with our Art Department collaborating with production designer Charlie Wood. They spent many months on its visual development and even as we began to build the actual asset we worked really closely with the Art Department. “The design became a jumping off point for us,” continues Kyle, “it really evolved through the desires of the director and became even more colourful and alien than it had been originally.”

First stop: the bar

Once inside the gang head to one of Knowhere’s bars where they find a games table featuring some weird beasts that’s just begging to be gambled on (more about that in our creature feature). While Drax, Rocket and Groot bet on the game Quill and Gamora slip away onto the balcony.

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The sequence was shot on bluescreen, which gave us an opportunity to frame it with a beautiful background that visually mimics the tone of their conversation. As things go well it flows into life, ebbing out of it as they go awry.

Above: The balcony scene with VFX

Above: The original bluescreen shoot

The Collector’s lab

Next came one of our biggest FX challenges on the show as we enter the Collector’s Lab, a room like that famous final shot of Raiders of the Lost Ark, but instead crammed with artefacts of the Marvel universe, extended by us in almost every direction. Here we see the effects of the power stone inside the orb as it engulfs the whole lab in black fire.

It was a tricky concept to realise – can something that’s black emit any light? “It was a real challenge to work out how it affects people, and probably the thing that evolved most over the course of the project,” says Kyle. “We tried a lot of different approaches, a particulate based dissolve, different cloth simulation ideas, different types of shattering. In the end it was a combination of several elements – a shatter with deformations so that it gave you this sense of veins that travel across the surface of the skin, creating pieces that break apart and then continue to break apart into smaller pieces. I think the finished effect really nailed what James was looking for.”

The fire and smoke simulations were done with our in-house fluid simulator fLush, which we honed even further to meet the demands of the show. “We looked at the Extremis effect we created for Iron Man, which used modelled veins, but here we had to find a way to do them procedurally so we could have growing veins that could open up to let the fire out,” says FX Supervisor Erwann Baudet.

Exploring the neighbourhood

Spat out back into the street in a cloud of fire, the Guardians are then thrown into a high-speed pursuit around Knowhere that explores every inch of the environment from every possible angle. “It’s so complex because there was a huge amount of geometry to contain in one space,” says Stuart Penn, who was Knowhere CG Supervisor with Nathan Walster.

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“It’s that enclosed thing that makes it difficult,” adds Nathan, “because there’s very little cheating allowed – from animation, to modelling, to lighting – as the camera moves around and you will see it in another shot. It’s a contained world that has to be completely correct.”

Above: Colour was the order of the day in Knowhere

The chase takes place at hundreds of miles an hour and so from shot to shot the action might travel a quarter of the way around the environment, meaning you soon see every part of it. The camera takes in all the geometry, from large-scale things such as the towers right down to individual railings, light fittings and doors.

It was built modularly, from 250 separate models based on art department designs such as towers, pillars, turbines, little huts and railings. The complete VFX Lego kit if you will. Each large element like a tower could be dressed with smaller ones like pipes to create the favela-like slums of each unique Knowhere district. Those 250 distinct models were used 85,000 times to build a city that numbered 1.2 billion polygons at render time. That’s a lot of Lego bricks. Then there’s the lighting. First the individual window lights, then the 10,000+ street lights placed by hand.

Above: Knowhere in development (bottom) and the final shot featuring a Necrocraft (top)

Animating the vehicles brought its own challenge. As it is essentially fighter planes flown by experienced pilots against our heroes in unfamiliar mining craft you had to feel that contrast. “Imagine the mining pods as super-charged forklift trucks, being driven by a formula one racer having to make it around some really tight corners” suggests pod chase Animation Supervisor, Dale Newton.

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The Necrocraft are a different matter entirely. “Believe it or not James Gunn gave us the reference of flies on shit, shot in slow motion,” says Dale. “It was an incredibly astute reference because if you watch flies they turn their heads in the direction they are going to fly to and then adjust their body and there’s this period of overshoot as they’re quite heavy compared to their thrust, it was perfect for the vehicles. Unfortunately we did have to look at a pile of shit for a long time to get the logic right.”

Above: Quill and Rocket take to the skies

“We really tried to draw you into it,” he continues, “we played the camera in most of the shots as if it was on another vehicle to really give a sense of being in there. We added camera shakes too, so there’s a bit of ambient movement as if you were on another ship but you got rocked by other vehicles coming by to you get this immersive feeling.”

A fun little problem to solve was how Rocket was going to fly the pod as they, understandably, weren’t designed with space raccoons in mind. In the end we got him to clamber right up on the control panel, which put him in an awesome pose, “almost like he’s riding a super bike” as Dale puts it.

The balance of the fight tips as our heroes realise they are essentially piloting wrecking balls – robust enough to smash through another vehicle unharmed. Smart thinking, but also the source of another big FX challenge for us: super detailed slow motion explosions.

Above: Rocket smashes through a Necrocraft

We enhanced fLush again to handle this, with our R&D and FX teams working together to make sure as much detail could be retained throughout the explosion. “The other difficulty is that no-one knows what a slow-motion explosion really looks like” explains FX Supervisor Erwann. “There have been lots of tests done at 1000 frames a second, but you can never see the level of detail we needed here. And of course no-one has ever filmed a spaceship crashing through another in slow-motion because it has never happened! It took us months to get it perfect and we needed a lot detail, smoke and fire, dust and debris, but it has turned out to be a very cool shot.”

'Guardians of the Galaxy' is in cinemas now.

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Image credit: Framestore/Disney