DICE is well known for creating extraordinary gameplay experiences grounded in realism. Now for the first time ever, they have integrated real-time ray tracing into a Battlefield title. DICE Technical Director Christian Holmquist discusses how it will empower truly realistic and dynamic reflections for Battlefield™ V on PC.
Lights, shadows and reflections are visual effects critical in any video games’ design process. Used both to enhance the atmosphere of environments players find themselves immersed in, and to provide important visual cues to the shape and material of 3D objects.
Throughout the Battlefield series, these components have always added an extra layer of gritty realism to gameplay. Just think how they lend themselves with dramatic effect to the devastated landscape and tattered ruins of Passchendaele, in Battlefield 1.
While the graphics of Battlefield have always been stunning, DICE wanted to push creative boundaries by going beyond traditional rasterization techniques.
“Rasterization is where a mesh of triangles that represents a 3D model of an object is converted into pixels on the screen,” DICE Technical Director Christian Holmquist explained.
These triangles have corners known as vertices that interact with the other vertices on that mesh. The rasterizer determines which pixels each triangle overlaps from the current view, and then evaluates the color of each pixel as it’s being drawn onto the screen.
But as Christian pointed out, “Rasterization can make it really hard for objects to interact with each other, because each triangle needs to know about a scene in its entirety, in order to correctly draw itself.”
However, a new approach to creating realistic visuals has been developed through real-time ray tracing. This technique which is associated with CG movies, will allow players to experience gameplay at a previously-unseen magnitude of graphical fidelity.
Christian excitedly described this as, “This is something we have been longing for, for a long time” said Christian. “We’re awesome at drawing an object in isolation and making it look almost perfect, but the interaction between objects is where ray tracing really comes into play for reflections, shadows and global illumination.”
Ray tracing also has the potential to push the boundaries of reflections, indirect lighting, ambient occlusion and Fresnel; how light reflects at different intensities based on grazing angles.
“The first time we implemented real-time ray tracing in on our Arctic Fjord and Rotterdam maps, it was amazing!” Christian recalled excitedly.
Essentially, an algorithm traces the path of light from many different viewpoints and simulates the way it interacts with 3D objects in the scene. As the ray moves through the scene it accumulates color and light information along the way from all objects it encounters. These interactions are then combined to produce the final color of a pixel, that will be displayed on screen.
Tracing from smooth surfaces like windows, cars, tanks, lamp posts, tiles, puddles and weapons accurately reflect elements of the environment around them.
3D objects that have microstructures, sub-structures, surface roughness, and are concave or transparent, also see reflections conform to them. Just as they would in real life, “reflections are there regardless of how a player moves around,” Christian added. “It doesn’t matter how complex the scene or surface is, with ray tracing the correct result is always achieved.”
“Although reflections won’t always be perfectly sharp, players can notice an explosion happening behind them and they’ll see blast particles reflected on the surface of a vehicle for example,” he noted.
With rasterization it’s not possible to efficiently reflect off-screen objects, which is a limitation with the standard Screen Space Reflection (SSR) technique. This reuses screen space pixel data to calculate reflections, which is commonly used to create subtle reflections on wet floor surfaces or in puddles - just cast your mind back to damp flight deck in Battlefield™ 3, when Lt. Jennifer Hawkins boards her F18 in Going Hunting.
But by rendering the game’s reflections in real-time, to align perfectly with other lit world sources and emissive materials, we achieve much more realistic and believable gameplay. As Christian put it, “The world of Battlefield V should feel real – period.”
Naturally there were challenges as Christian explained, “Transparency and translucency are always complicated with rendering, and with ray tracing its even more so. Explosions too are tricky, due to the sheer amount of particles that need to be added together to get the correct visual result.” Once those effects are in place the ray can return the correct color evaluation, which is something the Rendering Team at DICE invested a lot of work in.
After much work this has been achieved, and Christian likened these advancements in real-time ray tracing to “one of those things that happens maybe once every 10 years, like the generational jump in graphics we saw in the 1990’s, with the introduction of Hardware Acceleration 3D Graphics.”
When asked about for his thoughts on the future of ray tracing, Christian feels “players will see a much higher quality when it comes to interactions.” Like dynamic scenes having even better reflections, improved levels of detail, and how ray tracing will be used for shadows, ambient occlusion and diffuse global illumination.
State-of-the-art ray tracing architecture coupled with the dedicated work of DICE’s Rendering Team, makes Battlefield V on PC one of the most innovative Battlefield titles yet. Christian added, “Real-time ray tracing creates the most physical, immersive and visually-striking experience and we are extremely excited that Battlefield V will be the first game to utilize this technology. We’ve been working with NVIDIA hand in hand to bring ray tracing to our fans, and we’re committed to continually improving and optimizing DXR.”
Players can now experience a first release of DXR real-time ray tracing first hand in Battlefield V with NVIDIA’s GeForce RTX 20-series graphics cards
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