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Ray Tracing could be one of the most significant upgrades in computer graphics that we have seen in the present and for many years to come. As it's a very new technology and gradually being applied to major PC games, it's time we start understanding it. So, what exactly is Ray Tracing, what are its advantages, and which games are currently using Ray Tracing? Refer to the following introduction article for more information.
What is Ray Tracing?
To grasp this new technology, you need a brief understanding of its predecessors. Modern video games have long utilized a technique called rasterization to render images on the screen. The process involves your computer looking at the 3D scene, calculating distances to specific objects, where light begins to shine, and which object is in front of another. Using that information, it determines the color of each pixel on your screen, rendering the scene as a 2D image pixel by pixel.
Over time, developers have significantly enhanced this technology, enabling objects to cast basic shadows based on light sources or use tricks like surrounding occlusion to add independent shadows to light. However, most games don't truly simulate how light works in the real world—they merely fake it with this technique or another—making it challenging to create shadows and reflections realistically (that's why you rarely see mirrors in video games, and even when you do, the images inside the mirrors are often quite crude).
Ray Tracing, roughly translated as ray probing, is a rendering technique aimed at simulating how light interacts with objects, thereby creating more realistic shadows, reflections, and lighting effects. Tom Peterson, NVIDIA's Technical Marketing Director, described it as a physics-based approach to image rendering, contrasting with the artistic image rendering method.
In the real world, a light source, like a lamp in a bedroom, emits photons that bounce around the room until they reach your eyes. Ray Tracing reverses this process, tracing individual rays of light from the 'camera' of the scene and tracking how each ray interacts with different objects, then creating shadows and reflections before returning to the light source. This ensures that the computer doesn't waste processing power on objects that the camera doesn't see, while still producing much more realistic lighting effects.
This technique has been around for many years, and you've seen it countless times in computer-generated special effects films. Hollywood employs render farms to calculate Ray Tracing for scenes because they work with large datasets and perform a vast number of rays for the entire scene. It can take hours or even days to render even a short CG film scene using Ray Tracing. Previously, the amount of computation required made it unfeasible for video games because it needed to be done in real-time without affecting gameplay.
So what's special about GPU Ray Tracing for gamers?
While Ray Tracing may be commonplace in blockbuster Hollywood films, those effects are generated on extremely expensive rendering farms and can take hours (or even days) to render a single frame due to its complexity. On the other hand, video games need to be rendered on your console or PC in real-time, at 30 to 60 frames per second. That means advanced lighting techniques like this have never been easy to implement. In fact, when IGN first shared NVIDIA's initial Star Wars Ray Tracing demo from GDC in 2018, a critic noted: 'It's a good demo, but this lighting technique couldn't be done in real-time on affordable PCs right now, probably have to wait 5 to 10 more years.'
That demo ran on four Tesla V100 GPUs, and at NVIDIA's event months later, the company showcased it running on an RTX Quadro card. Certainly, Quadros still cost over six times more than the gaming-focused RTX 2080 Ti, but it's a remarkable leap in a short, astonishing period, and the prospect of real-time Ray Tracing for home gaming devices is getting closer to reality.
NVIDIA's GeForce RTX GPU lineup, released in 2018, is the first gaming graphics card to support real-time Ray Tracing - but they come with some caveats. These cards use what NVIDIA calls a 'hybrid rendering model' combining Ray Tracing with rasterization techniques, thanks to dedicated ray-tracing cores designed to compute the intersection of each ray. They also utilize special denoising algorithms and dedicated AI hardware, called 'Tensor Cores,' to reduce the number of rays that need to be traced. In other words, they're still 'cheating' a bit, as these cards won't necessarily trace every ray of light in the entire scene in real-time; however, the result is still a significant step forward compared to current rasterization methods.
The image below from NVIDIA helps you compare their new rendering model with straightforward rasterization - the way GPUs simply convert shapes into pixels on your screen.
However, these RT and Tensor cores aren't necessarily required to perform computations. Ultimately, NVIDIA has released Ray Tracing support for older GTX cards (at least those based on Pascal and Turing architectures) without the additional RT or Tensor cores. Nevertheless, without those cores, Ray Tracing will be much less efficient. Overall, performance is the biggest issue preventing Ray Tracing technology from becoming widespread.
How does Ray Tracing affect gaming performance?
When you enable Ray Tracing in supported PC games, you'll notice lower frame rates compared to when it's turned off. When testing early versions of Shadow of the Tomb Raider and Battlefield V with Ray Tracing in 2018, it was nearly impossible to achieve a consistent 60 FPS at 1920x1080 resolution - only ranging from about 30 to 50 FPS, despite using an RTX 2080 Ti GPU.
Since then, driver updates and game patches have significantly improved performance, easily achieving 60 FPS or more in Battlefield V, depending on your settings. But you'll still notice lower performance compared to when Ray Tracing is disabled: some games are affected up to 40%, while most others see a frame rate drop of about 15%.
The reason is that different games implement Ray Tracing in different ways. For example, Battlefield V uses Ray Tracing to create more realistic reflections on the sides of metal objects or in puddles on the ground. Shadow of the Tomb Raider primarily uses Ray Tracing to enhance its shadow quality. On the other hand, Metro: Exodus uses 'global illumination' to create more realistic lighting around you, leading to heavier performance impact compared to other games.
Real-time Ray Tracing in Battlefield V
Graphics cards that support Ray Tracing
In 2019, the only graphics card lineup to support real-time Ray Tracing came from NVIDIA. To experience a Ray Tracing enabled life, you should use at least one NVIDIA GeForce RTX 2060. However, if you can afford to splurge for the NVIDIA GeForce RTX 2080 Ti, you'll have a much better experience.
Below is a list of all officially supported graphics cards for real-time Ray Tracing as of now. They all have 'RTX' in their names.
- NVIDIA GeForce RTX 2060 | 30 RT cores | 6 GB GDDR6
- NVIDIA GeForce RTX 2060 Super | 34 RT cores | 8GB GDDR6
- NVIDIA GeForce RTX 2070 | 36 RT cores | 8 GB GDDR6
- NVIDIA GeForce RTX 2070 Super | 40 RT cores | 8GB GDDR6
- NVIDIA GeForce RTX 2080 | 46 RT cores | 8GB GDDR6
- NVIDIA GeForce RTX 2080 Super | 48 RT cores | 8GB GDDR6
- NVIDIA GeForce RTX 2080 Ti | 68 RT cores | 11 GB GDDR6
- NVIDIA Titan RTX | 72 RT cores | 24 GB GDDR6
Through the article above, I've introduced you to Ray Tracing - a still very new technology in the field of computer graphics. Of course, the article only provides a general overview, and there are many other aspects to discuss when it comes to a technology that could potentially change the future like this. But at least, you now understand what Ray Tracing is, the principles and performance of Ray Tracing, as well as the graphics card lineup supporting Ray Tracing as of now. Hopefully, the information shared above will be helpful to you!
