Ray tracing, have you ever heard this term? Although it’s been around for a long time in the movie industry, it’s still quite a confusing term, especially when it comes to video games.
It’s basically a technique that allows light to behave realistically. The idea of ray tracing is precisely to make games more realistic and immersive. Wouldn’t you be fascinated by the light that naturally bounces off objects? The indistinguishable line between reality and fantasy is undoubtedly appealing.
If you want to better understand ray tracing and its impact on games and a computer system, at a high level instead of going too deep into technical jargon, read on.
Imagine you are playing a PC game with the graphics turned up. Maybe it’s an open-world game like Cyberpunk 2077, where there are tons of objects and textures. As you duck down an alley to hide from your enemies and take a breather, you notice the pink light of a neon sign bouncing off the wet pavement.
It’s ray tracing. Your graphics card renders these hyper-realistic effects in real time, making the environment more dynamic. This means that the shadows will move according to the position of the sun and look softer.
But let’s dig a little deeper…
Ray tracing works by using an algorithm that traces light rays. When light hits an object or surface, the algorithm calculates how it interacts with it and how it interacts with other light rays bouncing off different surfaces.
The idea is to mimic the way the human eye processes light and shadows in real time. That’s why it looks so realistic. If you want to learn more about how ray tracing works, especially on Nvidia graphics cards, read the “RT Core” section of our article on Nvidia’s Turing GPUs (ray tracing made its debut on large graphics cards public with the GeForce RTX 20 series), or our original coverage of Microsoft’s DirectX ray tracing API, which serves as the basis for ray tracing on Windows systems.
Although ray tracing produces impressive results, it can be quite taxing on the GPU, as tracking all those light rays requires a huge amount of power. Moreover, tracing all these rays is very computationally expensive.
For this reason, most video games use traditional rasterization. It is much faster and does not consume as many resources. Even games that support ray tracing tend to rely on pixelation for the vast majority of visual effects, deploying state-of-the-art lighting effects for only a few key features.
Rasterization
Pixelation is how most video games are traditionally rendered. In a nutshell, it’s the process by which the GPU assembles a 3D scene. I like to think of GPU as sculptor and polygons as clay. Once the scene is set, these polygons are transformed into 2D pixels, then refined with shading, lighting, colors, and textures.
One of the limitations of pixelation is imprecise lighting effects. This technique cannot track light and calculate how it should hit virtual objects like ray tracing, forcing developers to spend a lot of work “simulating” lighting and its associated effects.
This is where ray tracing comes in, in supported games, although the frame rate still drops when even the limited ray tracing features kick in.
That’s why the rise of ray tracing has come with new image sampling technologies that help reduce the load on your graphics card and increase performance.
DLSS and FSR
DLSS stands for Nvidia’s Deep Learning Super Sampling. This technology works by rendering a game at a lower resolution and then upscaling those frames to the chosen resolution, using artificial intelligence and time data from multiple frames to help fill in the gaps.
The idea is to make the game as crisp as possible without sacrificing performance. What does this technology have to do with ray tracing? Well, it’s supposed to speed up ray tracing.
Since ray tracing puts a lot of strain on the GPU, most games drop below a respectable 60 frames per second. DLSS helps improve ray tracing by taking some of the stress off the GPU.
FSR stands for FidelityFX Super Resolution and is AMD’s scaling solution. Like Nvidia’s DLSS, FSR downscales the game and uses a “spatial” scaling technique to display the game at the chosen maximum resolution. In other words, your game will appear to be running at a higher resolution than it actually is.
However, FSR is a bit different from DLSS. For one thing, it runs on different generations of GPUs, including Nvidia’s GeForce cards. Plus, the source code is free for developers, which is great.
FSR’s spatial scaling has a more noticeable impact on visual quality than DLSS if set to its fastest performance options, but both work great when set to the Quality or Ultra presets Quality, especially on high-end screens.
The proof
If you want to see what ray tracing looks like in action in a game with full path tracing, check out the stream above. In the video, the PCWorld USA team explores Minecraft with ray tracing enabled. As you can see, there is a big difference in image quality.
The surface of the water is reflective and looks like glass, and the wooden huts cast realistic shadows on the ground. When PCWorld video director Adam Patrick Murray looks up at the sky underwater at 44:28, you almost have to squint because the midday sun is so bright. It projects directly into the water. This technology is charming and immersive, but it comes at a cost.
Ray tracing has a huge impact on performance because it requires more processing power from your system. The frame rate will drop, which is a real shame. This will happen even with the most powerful GPUs.
There aren’t many games that support ray tracing either, and those that generally only support ray tracing for a few effects – like reflections or shadows – rather than being entirely ray tracing, like the Minecraft video above.
That said, if you really care about aesthetics and have the right graphics card, you should give it a try. Realistic effects are truly amazing when done right.
Original article published in English on our sister site PCWorld USA.
