Simulation / Modeling / Design

Using Real-Time Ray Tracing in the Production of Fortnite Game Trailers

Fans of Fortnite look forward to the release of game trailers, which set the tone for upcoming in-game events. We talked with Andrew Harris (Studio CG Supervisor at Epic Games), Juan Cañada (Lead Programmer, Epic Games), and Juan Collado (FX Artist, Epic Games) to learn about how they are using real-time ray tracing in the production of these cinematic experiences. 

NVIDIA: How long have you been using ray tracing to create Fortnite trailers? Which was the first trailer to feature this technique? 

Andrew Harris: We’ve been using ray tracing on our internal trailer productions over the course of the past year. Our first use of ray tracing was on the John Wick Fortnite tie-in trailer, followed by a handful of short sketches that made their debut live at the Fortnite World Cup in July 2019. 

Fortnite X John Wick: Wick’s Bounty (May 2019) was the first Fortnite trailer to use real-time ray tracing. 

NVIDIA: Can you walk us through how the trailer development process has changed since you added ray tracing to your workflow? 

Andrew Harris: Since adding ray tracing to our workflow, one area that has noticeably improved has been our ability to visualize final lighting and shadows. Previously, we would achieve soft shadows using an array of spotlights, a slow and meticulous process that forced us to use simpler overall lighting during our first pass. With ray tracing, we’re able to visualize the finished product at an earlier stage than ever before. 

An added and surprising bonus has also been that, in many cases, scenes using ray-traced soft shadows have actually been more performant in comparison to scenes lit by the many non ray-traced lights required to achieve the same effect. 

NVIDIA: How has the look and feel of the trailers changed as a result of using ray tracing? 

Andrew Harris: When it comes to producing trailers for Fortnite, our vision has been to capture a level of quality close to what you’d expect from animated feature films. Achieving this level of quality is now much more straightforward. Accurate ray-traced shadows and GI make everything look more dimensional and realistic. Scenes feel like they exist in a real space. Plus, the combination of ray tracing with the benefit of a real-time workflow is one that can’t be overstated. 

NVIDIA: Which ray-tracing techniques are you using (i.e., shadows, global illumination, or reflections)? 

Andrew Harris: At one point or another, we’ve experimented with most of the ray-tracing techniques available in Unreal Engine during our trailer production, including shadows and reflections, skylighting, global illumination, and more.

NVIDIA: What roadblocks did you encounter when you first got started with ray tracing, and how did you overcome them? 

Andrew Harris: Real-time ray tracing technology is new, and ensuring that everything is both stable and performant took a bit of extra elbow grease. We overcame some of these challenges by designating a team of engineers and artists, whose role has been to detect problems and to identify solutions at an early stage. 

Delivering Fortnite trailers using ray tracing has been a massive test for Unreal Engine and our technologies, and everyone who uses our engine will benefit from our discoveries during this process. 

NVIDIA: Are there any practical learnings you could share from building these trailers with ray tracing that would specifically be helpful to animation studios? 

Andrew Harris: One area that we would recommend animation studios focus on would be optimization. It’s easy to slow a scene down with heavy or unoptimized geometry and effects, without improving its visual look. 

With Fortnite, trailer production benefits from the optimization and quality-control passes our assets get from being in-game, particularly ones designed for mobile, console, and PC. This ensures that our scenes start out fairly light and performant to begin with. 

Working in real time is all about having a fluid and iterative process. It’s been worth our effort, across all disciplines, to try and keep our scenes optimized. 

NVIDIA: Are there any learnings you could share that would specifically be helpful to game studios (who have to produce content that can run in real time)? 

Andrew Harris: As in film a decade ago, ray tracing will drastically alter whole content creation pipelines. Assets will be created differently, some of the optimizations that work for raster will be obsolete, and others will take their place. I recommend artists working at game studios begin learning techniques used in traditional cinematography. These worlds are blending together at a pace quicker than you’d expect. 

NVIDIA: Has the introduction of ray tracing allowed you to increase the number of trailers your team has been able to produce? 

Andrew Harris: While ray tracing hasn’t increased the quantity of trailers we’ve produced, it has surely increased the quality. With the power of ray tracing, we’re able to reach a level of polish that simply wasn’t possible previously. Admittedly, there’s been a learning curve, but with a little bit of know-how, we’ve hit the ground running and we haven’t looked back. 

NVIDIA: Could you describe the hardware you’re using to create these videos? 

Andrew Harris: We used single GPU configurations, mostly with NVIDIA RTX 2080 Ti graphics cards. In our trailer for Chapter 2 – Season 1, we switched to Titan RTX GPUs to be able to load the entire, massive, Fortnite map into the GPU. 

NVIDIA: What are you able to do now in trailer production that was impossible (or at least highly inefficient) before you were ray tracing? 

Juan Cañada: Ease of use and accuracy are two areas of improvement. Not only is lighting easier, but there has been a significant uptick in the accuracy of all aspects of lighting since we made the jump to ray-traced trailer production. 

NVIDIA: How have you managed the balancing act of adding ray tracing to adjust the aesthetic of your trailers, while still ensuring that the final product looks like the source material? 

Andrew Harris: As we mentioned earlier, we’ve aimed for a polished, feature animation-inspired look for our Fortnite trailers. Ray tracing helps to deliver this level of quality, so, for us, choosing ray tracing wasn’t a challenging decision. 

NVIDIA: Have you needed to build any custom assets to accommodate ray tracing? 

Juan Collado: To take full advantage of ray tracing, we have actively created a number of custom assets. Today, there are methods that define the visibility of assets in reflection or lighting passes. These methods allow us to influence lighting without having the object in its actual position. 

Custom assets, such as bounce cards, are also commonly used to create new shaders for highly reflective materials that incorporate physically accurate reflections. 

Lastly, we’ve created a variety of management Blueprints that give artists the ability to globally increase or decrease quality levels—allowing them to work more swiftly and to effectively balance interactivity with overall image fidelity.

NVIDIA: Did adding ray tracing change the way you light your scenes? 

Andrew Harris: Ray tracing didn’t change the way we light our scenes, and in many ways, for us, that’s the beauty of it. We may light the same way, but we now benefit from more intuitive control over the quality of the light and shadow. If I had to make a comparison I’d say that the experience is similar to lighting a live-action scene, and the final look comes together much, much quicker. 

Big thanks to NVIDIA for their pioneering efforts that have helped us reach this point!

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