How MoonRay Became the Hidden Superpower Behind ‘How To Train Your Dragon: The Hidden World’

The visuals for DreamWorks Animation’s ‘How To Train Your Dragon: The Hidden World’ were powered by the studio’s proprietary rendering tool MoonRay. Images © 2019 DreamWorks Animation LLC. All Rights Reserved.

The level of visual complexity in the finale of DreamWorks Animation’s popular film series, How to Train Your Dragon: The Hidden World, is evident even from the sneak peeks in the trailer. A shimmering white dragon, a female Night Fury, soars and curves around the spires filling the Nordic landscape of Berk. Our hero, Hiccup, dons stunning Dragon Suit armor made up entirely of dragon scales -- 3,620, to be exact. In one scene alone, more than 1,500 dragons fill the skies, each with their own size, color, and texture.

What viewers don’t know, however, is that hidden behind the fire breath and woven into the effervescent environment of the Hidden World, is the debut of one of the studio’s most innovative technologies: DreamWorks Animation’s new MoonRay renderer.

“I don’t think I’ve ever seen technology have such a significant impact on a film,” says visual effects supervisor Dave Walvoord. “Without MoonRay, How to Train Your Dragon: Hidden World wouldn’t be possible.”

The proprietary renderer was officially introduced to the world in a series of talks and papers at SIGGRAPH 2017 and HPG 2017. It made its first visual debut in DreamWorks Animation’s award-winning short film, Bilby, which debuted in 2018.

“The initial MoonRay vision was to develop a fast, interactive, and highly scalable renderer that could deliver the highest fidelity image with the ability to render anywhere,” says Robert Knaack, DreamWorks Animation’s director of research and development.

‘How To Train Your Dragon: The Hidden World’ visual effects supervisor Dave Walvoord.

Their motto, according to Knaack: “Keep all the lanes of all the cores of all the machines busy all the time with meaningful work.” The result is a high-speed renderer that features a robust shading system, interactive rendering, and multi-machine rendering capabilities that allow for nearly instantaneous results.

“We have thrown dozens of machines at a frame and we’ve seen linear scaling. Using ten machines on a frame allows it to come back ten times faster,” Knaack notes. “This is game-changing when it comes to rendering flexibility.”

How to Train Your Dragon: Hidden World is DreamWorks Animation’s first feature-length film to utilize MoonRay’s capabilities, and the result has proven to be a great success for the studio. Particularly in the lighting, environment, and detail throughout the film, the new technical abilities of MoonRay prove that Hiccup and his friends aren’t the only ones exploring a whole new world.

Let There Be Fire

Living in a world of dragons, there is naturally going to be lots of fire. In How to Train Your Dragon: Hidden World, many scenes throughout Berk and New Berk are lit by fire: candles, torches, dragon fire, even a chandelier of fire.

Pablo Valle, DreamWorks Animation’s head of lighting, knew from the beginning of the How to Train Your Dragon series that all the fire-lit sequences would pose a unique challenge to the lighting team. Before MoonRay, the artists created fire effects using red, yellow and orange lighting, rather than creating an “actual” fire. “We tried to mimic it using artificial fire laws,” he says, “but it wasn’t the real thing.”

Part of the reason “real” fire wasn’t possible was that it was too complicated and time-consuming to render. Valle uses the term “time-to-first-pixel,” the time it takes until the artists see the first pixel appear, to measure how fast the image is being rendered. “In the past, it was often days before an artist saw the first pixel,” he recounts. “Sometimes, by the time they got the image back, they’d forgotten their vision.”

Consequently, artists were often hesitant to try out ideas or experiment with lighting, Valle notes. Complex lighting, like fire, simply took too much time. With MoonRay, however, the time-to-first-pixel is nearly instantaneous. “Such a short turnaround allows the artists to focus on the art,” he says. “You can change your mind. You can try new things. You can explore. The speed has truly opened up a whole new universe for us.”

Part of that universe includes what Valle calls “real fire.” The Visual Effects department starts by creating the simulation, and the lighting team brings it to life. The result is a photorealistic fire that bounces and flickers as it would in real life. “What you get is an incredible subtlety of color, of flicker, of fire feeling alive,” says Valle. “You get a very believable scene that has all the range of real fire, with colors and shadows moving around.”

MoonRay’s ability to render in real-time has not only allowed artists the time to create fire, Valle says, but has also allowed for heightened creative freedom in all aspects of the film. “We have such a talented team,” he observes. “Now, they have the full box of crayons to play with.”

Larger Than Life

From the very beginning of the How to Train Your Dragon series, visual effects supervisor Dave Walvoord envisioned the story unfolding in a larger-than-life environment. He pictured it as if from the eyes of a child, where doorknobs are eye-level and trees are like giants.

With the technical capabilities of MoonRay, Walvoord’s vision is taken to the next level in the final film; particularly in the Hidden World environment, which has an elevation of 52,000 feet and is filled with towering trees, cascading waterfalls and glowing foliage. “These environments are much bigger, by far, than anything we’ve done before,” he says. “MoonRay gives us the ability to put everything we want into our world. It’s incredibly liberating for filmmakers.”

One example of the film’s grand scale is a scene that takes place in the Hall of Berk. Here, we see more than 300 characters dining together, many sporting beards or wearing fur -- two textures that require a lot of geometric and volumetric information. In addition, the camera is following a group of main characters walking through the crowd, meaning that each character in the scene is shown in high detail at some point. “Those are really complex challenges. We had details everywhere,” says Walvoord. “I’ve never made a movie that had this much detail in it.”

Working closely with Roger Deakins, cinematographer for Blade Runner 2049, Shawshank Redemption, Skyfall, Fargo and other feature films, Walvoord and his VFX team were able to create a scene that was detailed but not overstimulating for the audience. They worked with Valle and the lighting team to use light to accentuate certain details and draw the viewer’s eye to what is important. It’s a welcome problem to have; a renderer that can create images so realistic, the detail has to be handled as it is in the real world. “MoonRay gives us the capability to do whatever we wanted,” Walvoord comments. “And the artists didn’t just run with it. They flew with it.”

Detail and Design

That new artistic freedom that MoonRay provides is not only visible on a grand scale, but also in the minute details throughout the film. For instance, there are 2,000 unique character pieces in the film including hair and clothing. In the village of Berk, the blacksmith shop alone contains 1,097 unique props and assets. There are even 756 nails in Hiccup’s house. Many of these details may not ever be seen by the audience. Sometimes, as Walvoord describes, it’s more about how the film feels.

Take Hiccup’s Dragon Suit, for instance. In the film, the main characters use the scales of their dragons to create fireproof armor. Rather than design a new suit that mimics the dragon scales, the artists were able to actually take the dragon scales and glue them onto the armor. “We built those suits completely different because of MoonRay,” Walvoord says. “You can feel the authenticity.”

In a similar way, the artists were able to use MoonRay to create an environment that interacted with the characters in an authentic way. Instead of creating paths for the characters to take through the forest to save on rendering time, now we see the characters cut straight through the ferns and leaves. There’s moss on the rocks and pine needles crunching underfoot and a light breeze tossing their hair.

“We want the world to feel like it’s a continuation of the characters. We want the audience to be emotionally invested in everything,” Walvoord underscores. “You don’t think about technology supporting emotion in a story, but it really does.”

Telling the Story

This, perhaps most of all, is why MoonRay is such a transformative step forward; why the partnership between artistry and technology is a vital piece to creating masterful films, and why DreamWorks Animation is in equal parts a powerful technology company and an artists studio.

It’s because when technologists and artists work together, it furthers the ultimate mission of any DreamWorks Animation film: to tell a great story.

“Our job is to tell stories,” says Walvoord. “The How to Train Your Dragon series, at its heart, is a very heartfelt story. We need the technology to be at a certain level to carry that story.”

When that happens, when the technology pairs with artistry to turn creative vision into a reality as MoonRay has done in How to Train Your Dragon: Hidden World -- the possibilities are endless. “This film is truly our studio telling the story exactly how we wanted it to be told,” Walvoord says. “It’s the culmination of everything we’ve always wanted to do.”

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