Why Ray Tracing Is More Important Than You Realize

Many gamers seem to believe that ray tracing is nothing more than a fancier reflections technology, but they can hardly be more wrong. Ray tracing is not only the biggest leap in 3D game graphics technology in well over a decade, and not only can it lead to hugely improved immersion when used well, it can also lead to gameplay improvements and innovations. It is a technology here to stay, it is the present and the future, and in this article we will explain how while debunking other common misconceptions.

Ray tracing is a feature in Vulkan and DirectX 12 Ultimate. Any graphics card meeting those requirements can run ray tracing. This includes AMD’s RDNA 2 and Intel’s upcoming discrete graphics cards.

And no, NVIDIA isn’t completely dominant across the board in ray tracing performance. The RTX 3080 and above cannot currently be beaten, but once you start looking at the RX 6700 XT, RX 6800, RTX 3070 series and RTX 3060 Ti, AMD starts to pick up some victories at larger resolutions (although still not always) due to VRAM deficiencies with NVIDIA. Ray tracing performance is expected to be more competitive next generation.

Sure, in a number of games, the only thing ray tracing does is make reflections more accurate and incredibly more expensive. In such games, I wouldn’t even use the ray tracing. I did not use it on my RTX 3090 even. The recently released Metro Exodus: Enhanced Edition is a glimpse at what ray tracing will do for most games in the future. Educate yourself and watch this video if you haven’t.

As you can see, from a graphical standpoint, this technology does a hell of a lot more than just improve reflections. The ideal implementation is as demonstrated in the video: infinite bounce ray traced global illumination, the most significant graphical improvement ray tracing brings, as well as reflections, and also shadows ideally. When combined with quality PBR, it makes textures and models look more realistic too. When done right, it makes the game world seem alive, interactive, and real, with every light and shadow behaving realistically. Games like this make non-ray traced games, especially those not using global illumination, seem utterly static.

Another one of the coolest visual improvements is in the form of particle effects in a sci-fi game, if the particles use the same lighting and shadows of course. This is the nicest improvement that Quake II: RTX brings to the table, but imagine it in something like a Warhammer: 40,000 game! Or imagine ray traced weather effects in storms?

So, it is much more than just reflections, but at the same time it isn’t just shiny, fluffy graphics. When it comes to visual immersion in games, one of the common things that ruins it is the world being too static and not reacting to the player’s input. This is most commonly seen in the form of physics interaction (or rather the lack thereof), but it also applies to lighting and shadows where it is very common. For example, you’re using a flashlight in a game and it’s just not creating dynamic shadows. A common occurrence historically in games, and when you see it, it stands out like a sore thumb, especially if you’ve played games that aren’t guilty of this.

Interactive worlds, including interactive lighting, are strongly beneficial in immersing the player, even necessary for certain types of games like horror and stealth (both first person and isometric and everything in between). But people often overlook the potential gameplay improvements that ray tracing can bring to the table, so let’s dive into that.

 

DOOM 3 heavily experimented with dynamic lighting and using it quite simply in gameplay, as shadows cast by enemies can often give their position away. Ray traced global illumination takes that to another level; in fact even older, more primitive global illumination techniques that don’t use hardware ray tracing have demonstrated this.

For example, the global illumination and eye adaptation/HDR in Kingdom Come: Deliverance and Red Dead Redemption 2 allow the player to, for example, spot fires in the distance in low light situations, thus identifying people or camps where simpler lighting techniques wouldn’t allow you to see anything. This is really a life or death difference in a simulation game like Kingdom Come, where bandits tend to be more active at night and like to set up ambushes along roads. Thanks to the game’s global illumination, a keen eye can potentially lead to you seeing them before you walk blindly into your death.

With hardware ray tracing, this gets improved further. There could be situations where Kingdom Come’s or RDR 2’s global illumination isn’t advanced enough to reveal a certain light source that hardware ray traced infinite bounce global illumination would reveal. This even extends to simpler scenarios like clearing a room in any FPS game; players like to hide in shadowed corners in order to get the jump on you, but with proper use of ray tracing, they could be better illuminated by light sources, since light travels and bounces more realistically as shown in Digital Foundry’s Metro Exodus video above. These improvements aren’t exclusive to first person games either; a properly ray traced, globally illuminated dungeon would make for not only a big atmospheric improvement but can again seriously impact enemy detection (including AI detection in an advanced enough game) in a dungeon crawler or RPG, and most kinds of games really.

Now imagine these improvements in a game like the first two Thief games, where it is absolutely vital to both hear and see enemies before they see you. Thief, despite them being late 1990s games with primitive lighting techniques, has more complex mechanical light simulation than the vast majority of games due to its importance on gameplay. Hiding in the dark and spotting enemies and important objects is a must. A proper ray tracing implementation would make such a game infinitely more immersive, make it rely less on an HUD element and more on the visuals and atmosphere for sneaking around, and can even result in things like the player spotting a hard to see valuable object due to a reflection or glimmer caused by the ray traced lighting and reflection.

How about a daytime winter raid in a shooter, RTT, or TBT game? The sun is out and the skies clear, but the snow and reflective ice being heavy on the ground can make for a blinding atmosphere. This combined with a game that simulates camouflage (or a multiplayer game where it happens naturally) would result in characters wearing white camo having a particularly big advantage with proper ray tracing. How about a night time raid in a tactical shooter, where you might want to avoid reflective equipment because it can give your position away if a light or the moon catches it?

Or perhaps you’ll spot a target through a detailed ray traced reflection? And how about scopes or binoculars reflecting light in FPS games? In the Battlefield games that have this feature, scopes are basically just big spotlights visible in daytime. This is a cheap imitation that is actually unfair since it pretends to reflect light even when no light should be reflected at all. With proper ray tracing, this feature can be implemented correctly, resulting in snipers and spotters having to choose positions where sunlight won’t reflect off of their optics.

 

Target identification and planning around this isn’t the only gameplay improvement brought upon by ray tracing. Who knows what else developers will come up with? A proper ray tracing implementation can add additional challenge to a racing simulator during heavy rain when the sun is out, resulting in a wet, highly reflective track to the point where in some areas, the sun will reflect heavily off the track thus making track lines impossible to see, making it more difficult to hit an apex or even judge braking.

At most, it’s a temporary concern. Ray tracing is quite expensive, but there have been so many recent performance boosting technologies that can offset the performance penalty. Moreover, current generation graphics cards do still struggle with ray tracing performance, but the next generation will be exponentially faster. Hence why the ray tracing takeover hasn’t happened over night.

Ray tracing like in Metro Exodus: Enhanced Edition needs serious optimization to go along with it. We all know about NVIDIA DLSS and AMD FSR, and there’s Intel’s upcoming XeSS – these are absolutely needed for a ray traced game; at least just FSR for now, NVIDIA’s complex and proprietary DLSS has minimal benefit at this point. More than that though, we have mesh shaders which can lead to massive performance improvement, async compute, sampler feedback, proper multithreading to eliminate bottlenecks and let the GPU work, and more.

Metro pulls it off quite well, with its extremely advanced ray tracing implementation performing better than almost all other ray traced games (most of which having far simpler implementations). The ray tracing itself is very scalable in this game; for example, with ray tracing set to normal, you have 0.25 rays per pixel, on high it’s 0.5 rays per pixel, and on ultra it is 1 ray per pixel. This combined with the above mentioned optimizations and features such as Variable Rate Shading can make a ray traced-only game be very scalable, with the only minor caveat being that a ray tracing graphics card is a minimum requirement.

Optimize the rasterized side of the game, make way for the ray tracing. Then there’s virtual reality gaming, for which eye tracking will soon be a standard, and it is expected that games will use this to dynamically render content in your peripheral vision at a lower resolution, leading to enormous performance games in GPU strained scenes. Vulkan and DX12 prioritize optimization and efficiency above all, so let’s use it.

It Makes Game Development Easier

With ray traced global illumination, reflections, shadows, the lighting and shadows in a scene all take care of themselves once the lights are placed. No need to spend hours baking lights, level designers just have to position light sources how they want them and then move on. In a way, this makes video game scene lighting more like cinema/studio scene lighting, and amusingly enough the film industry would kill for static lighting to exist in reality while forward thinking gamers largely want it eliminated from gaming.

If a developer wants a scene to be lit a specific way all the time, they can just get more creative with the lighting placement, the material or emitter properties, and similar tricks we haven’t yet thought of. It shouldn’t be a major obstacle, and most of the time ray tracing will just be a pleasant convenience for game designers. 

 

Like every other game technology, there are games with good and bad implementations. Too many people have let poor ray tracing implementations like Battlefield V’s color their perception of the technology. The potential atmospheric improvements are both immense and obvious, as showcased by the above Metro Exodus video from Digital Foundry.

What’s less obvious to people are the potential gameplay improvements mentioned above. For the most part, they will become reality in time, as some can be experienced right now. Rather than dreading this technological improvement just because your computer can’t currently run it, let’s rejoice over this bit of evolution in game design, as evolution is exactly what this backwards industry needs.