Demystifying ray tracing for the next generation.
With a new generation of consoles on the horizon, curiosity definitely strikes when thinking about what they're going to bring to the table in terms of graphical power. Will they deliver a transformative jump for next-gen? Will they do native 4K with better textures and higher frame rates? Or is there a feature cooking in the background that we don't know about yet? We can count on one graphical capability that'll be new to the console world when PlayStation 5 and Xbox Scarlett (now officially known as Xbox Series X) ship late next year: ray tracing.
What Is Ray Tracing?
Ray tracing is an advanced method of illuminating 3D environments. With ray tracing, light sources cast out linear rays of light which then bounce off the surface it hits to another and to another until it reaches your eye, or the camera view in that 3D environment. Another factor ray tracing accounts for is the fact that different surfaces (like glass or water) will reflect, refract, and absorb light differently. These calculations lead to a more accurate representation of how light works in the real world.
Areas obstructed by objects and blocked from light rays are properly darkened as a result (meaning proper shadows) and a scene's illumination looks more realistic. Ambient light can also affect the darkness of shadows and ray tracing accounts for this, too--not every shadow is pitch black due to varied environmental illumination. Light will behave and react accordingly with mirrors, glass, and liquid as well. Scenes are able to represent changes to lighting conditions since rays are being cast and calculated in real time, making for realistic and dynamic environments.
It's much more clear when you see it for yourself, and Nvidia has an in-depth walkthrough of ray tracing in action:
Since light sources can cast thousands of rays and can bounce off multiple objects and surfaces with varying properties, it becomes a burdensome rendering technique for graphics processors. These are all calculations that your hardware has to process in real time and considering just how complex and intense ray tracing is, it's unreasonably difficult for current consoles to do it.
What It Takes To Do Ray Tracing
Ray tracing is currently making waves in the PC hardware space and first hit the consumer market last year with the launch of Nvidia's RTX family of video cards. These graphics cards are built with Nvidia's Turing GPU architecture which include dedicated processing cores--called RT Cores--to solely focus on ray tracing and work alongside the main GPU cores. Currently there are 8 video cards in the Nvidia RTX lineup equipped to handle ray tracing in PC games:
Ray tracing is also on a spectrum; Nvidia allows games with RTX ray tracing features to control how many rays can be cast in order to perform ray tracing. This means previous generation graphics cards can at least toy around with the tech, but it's largely inadvisable since you can take drastic hits to your framerate.
Xbox Series X And Xbox One News
The interesting aspect to next-generation consoles aiming for ray tracing is the fact that hardware manufacturer AMD will be building the graphics processors for both Xbox Scarlett and PS5. Currently, AMD does not have a GPU on the market specifically built for ray tracing and has only said that it has plans to dedicate the shader cores on its video cards to do ray tracing in the near future. Of course, future console hardware will be much different than what's currently available for PCs, so we'll have to wait until we get more details on how next-gen platforms will handle it.
But Why, Though?
You might be wondering, how is that any different from how light and shadows work in games without ray tracing? By comparison, the more common method, called rasterization, is a quicker way of doing lighting and shadows though it is more crude. But it doesn't account for the constant bouncing of light rays since it doesn't include real-time calculations. Nvidia has a more detailed explanation rasterization.
When it comes to how ray tracing actually affects a scene of a game, I often think about Nvidia's presentation of how ray tracing looks with Metro Exodus' global illumination. Without ray tracing, the inside of cabins are fairly lit, albeit flat and not entirely accurate in terms of how it would be in the real world. With ray tracing enabled, light that shines through the windows bounce around and illuminate the areas of the cabin properly, leaving certain corners darker in the players view:
Animated films, such as Pixar movies, have been using ray tracing for years. But of course, these are not interactive experiences that need to be rendered in real time, and film studios also have access to powerful machines that can render these scenes efficiently. But gaming hardware is slowly getting there. Sharper shadows, better ambient occlusion, and proper global illumination are all the benefits that animation and games get out of ray tracing.
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Many high-profile games have included Nvidia's RTX ray tracing tech and there will be more to come. Call of Duty: Modern Warfare is the latest release to use the tech and next year's highly-anticipated Cyberpunk 2077 will take advantage of it, too. Developers typically work alongside Nvidia to implement it properly, and so far, here are a few of the big games:
- Call of Duty: Modern Warfare
- Battlefield V
- Metro Exodus
- Shadow of the Tomb Raider
- Cyberpunk 2077 (upcoming)
- Atomic Heart (upcoming)
- Quake II
The term ray tracing is increasingly getting thrown around in discussions about the next generation of gaming hardware, and if you haven't been keeping up with the PC hardware then you may be lost; hopefully we've at least provided a fundamental understanding of it. To put it simply, ray tracing is a graphical rendering technique that has light sources casting rays that behaving as they would in the real world to provide more realistic looking shadows, reflections, and overall illumination--however, it's hardware-intensive.
We don't know much about how next-gen consoles will be handling ray tracing, but don't expect every PS5 and Scarlett game to include it or run the full gamut of ray tracing features. The tech is still in its early days and only a handful of PC games have it implemented today. If you want to get into the weeds of ray tracing, you can check out this Nvidia developer blog that explains the heavy technical details.