What Is RTX? - A Short Guide to Nvidia’s Biggest Feature

If you’ve been a PC gamer during the past couple of years, chances are you’ve heard about ray-tracing technology. If you’re an Nvidia fan, you’ve probably also seen the term “RTX” plastered just about everywhere in the company’s marketing materials, from support websites and drivers to the GPU packaging.

What is RTX, though? Does it differ from ray tracing, and if so - how? Can it make you a better gamer, or is it just a silly gimmick designed to drive up the already ridiculous prices at which graphics cards are sold these days? The answer may not be as simple as it appears to be. Let us first explain what ray-tracing tech is all about, how it works, and its potential benefits in gaming. Then, we can get into how RTX and ray tracing are related. Let’s get started, shall we? 

What Is Ray Tracing?

Ray tracing is a rendering technique used in computer graphics to create a more realistic lighting and shadow simulation. It works by tracing the path of light as it travels around the scene, translating it into pixels within the image plane, and simulating light effects on the virtual objects in its path. 

Ray tracing is used for highly realistic depictions of real-time lighting but comes with a high computational cost. This has made the technology popular for movie and animated movie visual effects but highly impractical for real-time implementation in gaming. However, in recent years, both AMD and Nvidia successfully brought ray-tracing graphics cards to the PC gaming market.

To have ray tracing clearly explained, we need to mention what the technology can do when it comes to lighting effects. The list is long, seeing that it can be used to simulate various optical effects through ray tracing, including light refraction and reflection, soft shadowing, chromatic aberration, light scattering, and more.

It’s not restricted to visual effects, either: Sound waves can be traced in a similar way to light waves, creating much more realistic echo and reverberation effects, along with accurate 3D audio positioning.

What Is RTX?

RTX is proprietary technology made by Nvidia to harness the power of ray tracing in computer 3D graphics. It’s a complex visual computing platform designed to create scientific visualizations, large-scale models, and more. It’s also used to enable real-time ray tracing in games and other 3D applications. 

Until Nvidia introduced the first RTX graphics cards in 2018, ray tracing had been the domain of 3D renderings and movie special effects. Lighting in games had previously been done exclusively through a mix of direct sources and precalculated indirect distribution. While much less resource-intensive than real-time calculation and rendering, it creates less realistic light sources and shadows.

So, what does RTX stand for? While Nvidia doesn’t like to advertise the full name much, RTX simply means Ray Tracing Xtreme. Nvidia uses it to differentiate its newer graphics cards from the older models. It’s not just a cosmetic name difference - an RTX graphics card has specially built tensor cores designed from the ground up to facilitate real-time ray tracing. 

Although earlier GTX cards (Pascal series, for example) have subsequently received driver support for RTX technology and GTX ray tracing is technically possible, the performance hit on architectures not built for ray tracing is too severe for most gaming applications. Ray-tracing performance is, therefore, the most significant difference between RTX and GTX cards, along with the token increases in general-purpose computing power.

Global Illumination and Ray-Traced Reflections

Global illumination quality and better object reflection are the two most notable improvements to light and shadow rendering with RTX technology. Traditional rendering methods employ various tricks, such as preplaced lights, reflective shadowmaps, and precomputed lightmaps to simulate lighting interactions within a scene. 

The main downside to this approach is that dynamic light doesn’t bounce and doesn’t affect areas beyond its initial target. Therefore, lit objects don’t reflect light off themselves, and diffuse lighting is approximated and created artificially with additional light sources.

Developers who know how to use ray tracing and have the appropriate technology at their fingertips can now create much more realistic scenes with dynamic direct and indirect lighting updated in real-time.

The situation is similar when it comes to reflection quality. There are many “RTX on RTX off” clips on YouTube showcasing the inherent superiority of the ray-tracing method compared to the traditional screen-space reflections.  

The most noticeable difference is that screen-space reflections only show reflections of those objects or people already visible in the frame. Objects behind, below, or otherwise out of the camera’s focus get fake reflections in the form of low-resolution reflective cubemaps. 

The difference between having RTX on vs. off is especially apparent when viewing large reflective objects. Repetition of the exact same fake reflection can occur on multiple reflective surfaces. Furthermore, cubemap replacements for accurate real-time reflections can’t display occluded details, such as objects hidden behind other objects or people, and they tend to disappear on player or camera movement.

Ray Tracing and Performance - Can AMD Compete With Nvidia in 2022?

We’ve already talked about the severe strain that real-time ray tracing puts on graphics cards. Making millions of calculations every millisecond, all in real-time, presents a challenge for even the most powerful GPUs on the market. What is real-time ray tracing truly like, though? Just how much of a penalty to performance can we expect in 2021? 

That largely depends on your chosen ray-tracing GPU. When Nvidia’s first RTX graphics cards hit the market, much fuss was made about the technology. In reality, it came with borderline crippling performance drops, to the tune of 4k-capable cards not being able to hit 1080p 60 fps reliably. Things have since improved dramatically, thanks to fine-tuning the intensity of the ray-tracing effects (solid or transparent reflections, diffuse lighting, contact shadows, and so on), and another proprietary tech by Nvidia - Deep Learning and Super Sampling, or DLSS.

We’ve already mentioned what RTX stands for. However, the tensor cores within Nvidia’s Turing and Ampere cards also offer a sophisticated system of utilizing AI and machine learning to fake higher-resolution images with greater accuracy and detail but without the rendering strain on your graphics card. Typical RTX implementations in games produce anywhere between 20% and 50% hits to framerates, so simulating a higher display resolution without having to actually process increased pixel counts goes a long way toward making ray tracing viable in gaming.

This is also the primary reason why AMD’s 6000 series (“Big Navi”) cards are not yet up to scratch when it comes to RTX gaming on PC or consoles. Remember the difference between the GTX and RTX models we’ve talked about before? The same thing applies to AMD cards - no dedicated tensor cores, so no DLSS and weaker ray-tracing support out of the box. 

That being said, AMD is working on its own open-source alternative to DLSS technology, which, when ready, should be more than a match for Nvidia’s implementation. AMD is still one generation behind its archrival regarding ray-tracing technology, but we have no doubt it will catch up within a generation or two at most. Ray tracing is the future of gaming; it’s just one that is still several years from mass implementation at this point.