How Ray Tracing Helps Battlefield 5, Metro Exodus And More

By Alex Walker on at

When Nvidia announced their real time ray tracing feature set at Gamescom, the big question looming over the announcement was the games. And during an Editor's Day outlining various aspects of the Turing architecture, developers working on ControlMetro ExodusBattlefield 5Mechwarrior 5: Mercenaries and other games explained precisely what gamers could expect.

Every game is different, and each of the games shown off all had different implementations of the new technology announced. But the general messaging was the same: traditional lighting techniques for video games don't allow for sharp, accurate reflections; the methods used today often result in a lot of artefacts, and high quality shadows are difficult to replicate in games with dynamic environments and changing times of day.

Screen space reflections, for instance, were mentioned frequently as a pressing issue. The problem with existing screen space reflections is that reflections can only be rendered with the information that's available on the screen at the current moment in time.

Assetto Corsa Competizione was a useful demonstration. Without real time ray tracing, it wasn't possible to accurately replicate reflections of things you'd expect to see in a car door or window, like a grandstand off-screen or a trailing car out of shot — because if those objects aren't visible in the current scene, existing techniques don't have the information to render that properly on-screen.

Two developers from DICE — Jonas Gammelhom and Christian Holmquist — then went more into detail about Battlefield V's implementation of RTX effects, going over the ray tracing demo showcased earlier in the week.

One benefit that wasn't outlined in the livestream, though, was what happens when a player aims down the sights. Typically, the sights and end of the barrel collides with the shadows, creating a jarring effect as the shadows aren't able to smoothly penetrate through. With ray tracing enabled, the shadows blend behind the iron sights much more naturally.

Remedy Entertainment — makers of Max Payne and Quantum Break — then took the stage, showcasing the difference in visuals between their E3 reveal with and without ray tracing.

It was especially prominent in an indoor scene, where the sun is shining inwards on a series of chairs facing a desk. With the normal lighting techniques, the chairs and desk are missing soft shadows. Ray tracing (or more specifically, the performance benefits of ray tracing with the Turing GPUs) allows the chairs to have soft shadows around their feet, eliminating the effect that causes objects and characters in games to appear like they're hovering slightly above a surface, rather than being placed or standing on top.

Earlier this week, Remedy released a recut of their official E3 trailer, using the Nvidia RTX effects in place of the standard shadow maps shown earlier. You can compare the two videos below.

Piranha Games president Russ Bullock then took the stage to talk about MechWarrior 5: Mercenaries, which is due out next year (and will get a precise release date at MechCon).

Mercenaries, which is due out next year (and will get a precise release date at MechCon).

Ben Archard, rendering programmer on Metro Exodus, then discussed 4A Games' implementation of the technology. After walking through other upgrades made to 4A's in-house engine for Exodus — like more weapon customisation, seasonal changes and a day/night cycle — they discussed how ray tracing allows the studio to strip their lighting system "back to basics" and a "single light".

Archard then referred to an indoor scene from Metro Exodus, showing the difference in direct illumination versus ray tracing. Without ray tracing, the majority of the room was lacking lighting entirely, making it difficult to identify textures and details if the object wasn't directly hit by light rays coming through the window.

With the RTX effects enabled: walls were clearer, more details could be seen in areas of the room that weren't directly lit, and there was a gradation of light throughout the room.

"We've finally got over what is, without doubt, the biggest hurdle in games development history — real time ray tracing," Archard said.