Game of Thrones: Season 6 Case Study

Case Study

Game of Thrones: Season 6

Following on from season five of HBO’s Game of Thrones, Image Engine was asked to return to Westeros and Essos once again for the show’s epic sixth season. Read on to learn how the team built the Citadel, reinforced the Wall, and finally offed that one character everybody loves to hate… Spoiler alert!

Back on the throne

Game of Thrones is no easy show to deliver. Over the past six years its post-production values have increased alongside the size of its world. Each new far-flung location revealed, from the icy ramparts of the Wall to the towering spires of the Citadel, requires a new raft of visual trickery to help bring the environments to life.

However, Game of Thrones has ensured that efficiency and organisation in production has scaled with the aspirations of its visual effects.

“Right from the beginning, we knew what to expect on Game of Thrones season six,” begins Image Engine visual effects supervisor Mat Krentz, who worked alongside the Image Engine team, HBO visual effects supervisor Joe Bauer, and visual effects producer Steve Kullback.

“The production was always prepared with on-set reference; their editorial team was constantly on top of what was going on with shots; and everyone was really fun to work with to boot!” he continues. “There was never any question of where the show was at. It was all incredibly streamlined.”

And an efficient production means a quality one. For Game of Thrones season six, the Image Engine team held nothing back in the quest for truly spectacular visuals across the plains of Westeros.

The seat of the Order of Maesters

One of the new locations revealed in Game of Thrones’ season six is the Citadel – the seat of the Order of Maesters situated in the southwest city of Oldtown.

Housing an enormous book collection and a labyrinth of corridors, the Citadel is an incredible space, but one that presented a variety of creative challenges. For starters, Image Engine needed to communicate with vastness of the library, which was described to the team as “the biggest library that you’ve ever seen”.

In fact, the Citadel library needed to be 10 times larger than the real library reference that had been collected. To achieve the effect, Image Engine artists took the reference and roughed out the placement of bookshelves and hallways in CG, then proceeded to populate the library with a countless array of books, stretching off into the dark chambers of the Citadel.

“We had point cloud data for every bookshelf, and for each one of those points we instanced a random library of shelves of books and scrolls,” explains Image Engine CG supervisor Edmond Engelbrecht. “We used a lot of procedural techniques to swap those books around so you didn’t get a lot of them repeating. It made it feel all the more like a real repository of knowledge.”

Of course, the Citadel isn’t just a home for books, but also those who read them. The mighty structure stands as the official training institution for the novice maesters, who peruse the endless tomes and absorb a world’s worth of knowledge.

Image Engine conducted a motion capture shoot that would drive animation of multiple CG maesters as they browsed the enormous library. “Edmond even got in the suit at one point!” exclaims Krentz, “Using that mo-cap data made it easier to populate the Citadel’s library with the maesters, scattering them around the bookshelves and giving a sense of life to the space.”


Another interesting element of the Citadel environment was its lighting. Here, a huge astrolabe hangs from the rafters, and is used to bounce light in any direction through the enormous Citadel interior. It’s a beautiful and atmospheric effect, but one that required a great deal of technical thinking; primitive lighting wouldn’t be up to the task, given that it would result in caustics hitting hard surfaces.

Image Engine therefore devised a unique solution for the astrolabe’s effects. Compositing lead Edwin Holdsworth brought in a projector and lenses to the Image Engine studio to test and play with the caustics it produced, working out what would play best in the scene while retaining the location’s cavernous ambience.

“We were provided passes from the lighting team that would enable us to implement caustics in a realistic manner,” says Holdsworth. “We were then able to use the real 2D elements with chromatic aberration, diffraction patterns, and that beautiful light distortion that you only really get with glass and mirrors that are slightly imperfect. That was ideal.

“On top of all that, we needed to create a sense of depth in the comp,” he adds. “For that we used all the depth information given to us by 3D. We were able to incorporate all of the beams from the astrolabe VFX into the particle system in NUKE. We could get the animation elements and transfer that into NUKE, turning it into the 2D effect that’s witnessed on screen.”

Becoming Bran the Builder

The Citadel was just one of the impressive locations built by Image Engine for Game of Thrones season six. Another saw Image Engine return to the North, Castle Black and the towering 300-mile Wall.

Using assets from its work on season five, Image Engine once again created establishing shots and set extensions for the Night’s Watch headquarters, but this time pushed the effects further still, working on increasingly complex camera moves while adding more detail.


The Wall’s icy surface, for example, benefited from improved procedural texturing and sub-surface scattering: “Procedurals are harder to achieve than hand painting the asset, and the Wall was a very complicated network of textures and distortions!” says Engelbrecht. “It took a while to get it going, but we’ve done enough procedural in the past to know that the payoff is always really good. It ended up working really well: the wall looked like a real sheet of monumental ice.”


Other locations included aerial views of a wildling camp, achieved as a matte painting comprised of full-motion live-action clips for tents, people, smoke and atmosphere.

Image Engine was also once again responsible for shots involving Wun Weg Wun Dar Wun – the wildling giant that sides with Jon Snow. Again, the character and his huge size was made possible via greenscreen and motion control photography.

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“One shot in particular for Wun Wun was really fun,” recalls Krentz. “It involved him grabbing one of the men from the Night’s Watch and smashing him into a wall, then throwing him into the ground. That required a digi-double replacement of the unfortunate victim, along with a great deal of gore and blood passes.”

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Blood of my blood

Blood and gore was in fact something of a specialty for the Image Engine team, who built on the effects they previously delivered for season five.

Across the majority of episodes, image Engine took detailed stunt and practical effects and augmented them, giving each shot for the that visceral Game of Thrones touch.

Most of the work began with weapons, including the extension of sword props used on set or the insertion of elements like digital arrows. “If a weapon prop is half-built for a scene and we needed to extend that, then our matchmove team would typically do the animation of the weapon,” explains Krentz. “From there we bring it over to our lighting team, who make sure everything is properly integrated and looks as it should.”

Although the Image Engine team had plenty of blood elements provided to them by production, some of these splashes, splats and arcs of crimson weren’t enough to sell the ferocity of a scene. For those moments, Image Engine chose to shoot its own elements.

“Some shots were really specific, like someone getting their head smashed directly against a wall,” says Holdsworth. “To get the look right for that we filmed real meat being smashed. We used the same technique for shots where one character has their hand pulled apart. The best way to match the level of gore needed was to pull some meat apart, and use that in the comp. It all felt more realistic that way!”

Image Engine’s blood and gore enhancements extended to digital make-up work. Wounds on the resurrected body of Jon Snow, for example, were part of the practical on-set make-up, but were augmented with CG to feel much deeper. Meanwhile, the return of Benjen Stark saw the studio detail frost-bitten and grotesque additions to areas of his face.

And then there was that walking powerhouse of meat and gristle, The Mountain, whom Image Engine had previously ‘zombified’ for season five. Image Engine needed to enhance the actor’s practical make-up once again, but this time on a completely unmasked face.

“It amounted to a 50 per cent enhancement of the practical make-up,” says Holdsworth. “However, the biggest part of the work was changing the lighting. The production wanted The Mountain’s face to be revealed from out of the darkness and into a pool of light. We used the 3D matchmove to track the geometry of his face and some lights in NUKE, finally revealing his visage to the audience.”

The (un)fortunate fate of Ramsay Bolton

Game of Thrones wouldn’t be Game of Thrones without its villains, and perhaps the show’s greatest feat was introducing one that viewers hated more than the already despised Joffrey Baratheon: House Bolton’s Ramsay Bolton, who deftly balances sheer brutality with with a knack for being exasperatingly annoying.

Ramsay’s comeuppance was always on the cards, and it was Image Engine that got to deliver one of season six’s most satisfying scenes – his final, grisly demise, as the character is devoured alive by his own starving hounds.

Image Engine augmented actor Iwan Rheon’s jaw as the first dog attacks: “They shot the scene with multiple takes,” explains Krentz. “They did a pass of the dog on greenscreen, then Ramsay on greenscreen, and then we also had a background plate, which we put together.”

Image Engine’s artists also built a CG jaw and animated it to show the flesh ripping between Ramsay’s skin and gums. The initial result was so gruesome that Image Engine slightly scaled back the gore – hinting that perhaps the artists had something of a distaste for Ramsay themselves: “We pulled back on the CG work and we eventually did a 2D composite instead, which worked out great.”

The overall result was another season of Game of Thrones that balanced bloodiness and beauty in wealth of high-end visual effects – along with a darkly enjoyable end to one of the show’s most evil characters.

“Game of Thrones is such a lavishly detailed world, and we were truly thrilled to bring George R.R. Martin’s imagination to life on the screen once again,” says Image Engine visual effects executive producer Shawn Walsh. “Not only that, but it was a pleasure to work with clients who make such great partners. Visual effects work of this calibre is so challenging, so to have folks who truly understand the importance of the attention to detail in process is a blessing. Our second run with Joe and Steve has lived up to the first – we sincerely hope to return to Westeros once again!”

Game of Thrones Infographic - Image Engine Kills and Sims