Nvidia’s RTX GPU Series: How Real-Time Ray Tracing Changes Gaming

by / Wednesday, 31 October 2018 / Published in Latest News

Earlier this year, Nvidia unveiled its new line of Graphics Processing Units (GPUs), under the new name: RTX. This is an upgrade from the earlier GTX series of GPUs, but the branding isn’t the only change.

Nvidia has now equipped these GPUs with the capability to carry out real time ray tracing. But what is ray tracing and why is it so important?

What Came Before Ray Tracing?

The word “rendering” is used quite a lot when discussing graphics cards or gaming. The process of rendering involves converting a three-dimensional object into a two dimensional image that will appear realistic on your screen. Games are interactive, and they render objects as a player’s movement changes the perspective on the screen.

This means it’s necessary to have a way to ensure the graphics look realistic. Developers have achieved this using real time rendering, but for decades, it has used the same technology: rasterization.

Rasterization is a technology that, at the core, relies on triangles. It sees 3D objects as a large collection of polygons made out of triangles. It gathers various kinds of data, like position, color, texture, and such, from the three points AKA vertices of the triangles.

Not all of this data is needed, so it then refines the data. It sets the screen as the frame of reference, and it then determines how to display the pixels. Once this is done, there’s a bit of processing and the image shows up on your screen. It’s a lot of work, but the GPUs (how to tell a GPU, CPU, and APU apart) have enough power to get it done within a fraction of a second, and refresh it multiple times within a second to make the motion appear very smooth.

Ray Tracing vs. Rasterization

In the real world, you’re able to see things as a result of light hitting them. Real world lighting is very complex, with each ray of light reflecting and refracting multiple times before it reaches our eyes, making us see the high amount of detail. Replicating this is a very hard job, but with ray tracing, the technology is now closer than ever.

Ray Tracing versus Rasterization comparison using teacups
Image Credit: Intel

As the name itself suggests, ray tracing relies on tracing every single ray of light hitting objects in a virtual three-dimensional scene. Ray tracing will follow the path of light rays from the light source, to the objects, and every reflection and refraction they go through, before finally reaching the screen.

If there are multiple light sources, ray tracing will account for all of them. Instead of treating every pixel as a point on a mesh of polygons, like rasterization does, ray tracing treats every pixel as a ray of light, which is comparable to how the human eye actually sees things.

Why Is Ray Tracing Suddenly Relevant Now?

The film and animation industry already uses ray tracing technology for rendering scenes to make them look as realistic as possible. Note that this does not require real-time ray tracing; your current GPU could probably handle ray tracing, too.

However, depending upon how heavy the scene you are trying to render is, it could take several days to render just a few seconds of three-dimensional imagery. In gaming, GPUs have to render the scenes on the go. The primary requirement for this is hardware capable of doing that in real time.

Of course, ray tracing requires much more processing than rasterization needs, and thus is a GPU-intensive task. Using ray tracing for every part of a virtual scene is the ideal way to get the most realistic-looking picture. However, it’s often only used for selected parts of a scene. The GPU processes the rest of the scene through rasterization.

This brings us to Nvidia’s approach with its the latest series of GPUs, and specifically what they do with RTX.

How Does Nvidia’s RTX GPU Work?

Nvidia’s latest generation of GPUs, also called Turing, is an obvious improvement on paper. Nvidia manufactures these with a new, smaller 12 nano-meter process. They also claim to be 50% more powerful, and 10 times as fast as the previous generation. However these numbers don’t mean much.

What is important is how Nvidia has changed the basic structure of the GPU.

Nvidia Pascal and Turing architectures compared
Image Credit: Nvidia

These new GPUs carry the usual CUDA cores that Nvidia has been using for the previous generations. In addition, they also come with dedicated “Tensor” cores, for machine learning, and “RT” cores for, well, you guessed it, ray tracing. To sum it up, Nvidia has based these GPUs on a new architecture that is smarter, and has hardware specifically dedicated to ray tracing, which is a first.

All this is used in combination to speed up ray tracing and get it to work in real time.

To make use of this new hardware efficiently, Nvidia has a bunch of software to go along with it. Nvidia OptiX is one that helps make the best of the hardware’s ray tracing capabilities. It also has an “AI-accelerated denoiser”. Now, as you know, ray tracing relies on using light to determine how a virtual image looks.

Because of this, there is bound to be some noise in areas that have little to no light. The denoiser helps get rid of that. Nvidia is also working on adding support to ray tracing to the Vulkan API.

Nvidia isn’t alone in this, either. You might know about Microsoft’s DirectX, a prerequisite to run many a games on Windows (how to install and upgrade DirectX). Microsoft has announced an extension to the latest version of it now, called DirectX Ray Tracing (DXR). This aims to help bring in software support for developers to adapt their game to take the fullest advantage of Nvidia’s RTX.

RTX will use the new hardware power and ray tracing capabilities along with the old reliable rasterization and other related processes, to deliver a gaming experience that will look more realistic than ever.

Is Ray Tracing the Answer to Next-Gen Graphics?

Well, not quite. Ray tracing hasn’t been used in a day-to-day consumer scenario before. That’s why it will take some time for the consumer industry to adapt this technology. Developers have already begun integrating this technology into their games. However, only a handful of games support it at the time of writing.

So in case you’ve been thinking of upgrading your GPU, waiting for a while to see how the technology progresses might be the better option. In any case, ray tracing is likely to be the future of gaming. It may end up being through RTX, or through some other equivalent technology released sometime in the future.

Only time will tell. In the meantime, check out this nifty breakdown of the differences between TVs, gaming monitors, and Nvidia’s BFGD displays.

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