Obviously and as the name (RTX) suggests, these two technologies have a lot to do with the new NVIDIA graphics architectures and, of course, they are only compatible with graphics cards GeForce RTX of the brand, which are those that incorporate dedicated hardware for ray tracing. Also as the name suggests, both technologies have to do with the scene lighting that we see in games, and they aim to create environments that are much more realistic in terms of lighting.
Why are specific lighting technologies necessary?
Actually, it is not that they are “necessary” as such, but they do fulfill the primary objective of game developers: to improve the visual quality of their creations. Lighting in games has always been a very important aspect, since thanks to it, much more realistic environments can be created in which, for example, sunlight is not just a source of light in the sky, but is able to create an environment of lights, shadows and reflections that varies in real time not only depending on the location of the star king in the scene, but also on the movements of the character (for example, in the shadow of the character himself).
Until now, game developers had not put too much emphasis on this visual aspect, but with the advent of dedicated hardware for ray tracing they have found the perfect excuse to be able to implement it without this having a too great impact on performance of the games; After all, as much as your game is a graphic marvel, if users are not going to be able to enjoy it with decent performance, there is no point in spending resources on it, right?
The arrival of Ray Tracing has brought under its arm the implementation of what we could consider as sub-technologies, among which we find RTXGI and RTXDI which are the ones that we are going to talk about next, both obviously based on ray tracing and which are quite twinned but each one with a different purpose. Let’s see it.
RTXDI and RTXGI, two different technologies that go hand in hand
Let’s start with the technology RTX Global Illumination (RTXGI), which as its name suggests has to do with the global lighting of the scenes. NVIDIA defines it as “Leveraging the power of ray tracing, RTX Global Illumination provides scalable solutions for calculating indirect lighting and its multiple bounces without processing latencies, light leakage or high performance costs per frame.”
This means that RTXGI provides developers with a set of tools (SDK) by which they can easily program how indirect light hits objects, how it bounces (even with multiple bounces, something that happens in reflective surfaces like water or mirrors) and how are the shadows that these bounces of light generate.
All this, according to NVIDIA, can be done without increasing the latency of the frames (what they call “bake time”) and without having an impact on the performance of the game, thanks as we have commented before to that dedicated hardware for plotting. of rays that incorporate the RTX graphics of the brand. Depending on the brand, RTXGI is (just like RTXDI) compatible with all DXR (DirectX Ray Tracing) enabled GPUs, and they say it’s the ideal starting point to bring the benefits of ray tracing to any developer’s titles.
Just because NVIDIA ensures that this technology does not have a performance impact does not mean that the more powerful the GPU, the better the result. As you can see in the graph above, courtesy of NVIDIA itself, an RTX 3080 is capable of generating many more iterations per millisecond than an RTX 2080 Ti, and this in turn many more than an RTX 2080 SUPER. As you can see, the capacity of a GTX 1080 Ti that does not have dedicated hardware for it is very, very far behind.
For its part, technology NVIDIA RTXDI (RTX Direct Illumination) It is a kind of counterpart to the previous one, but instead of having to do with indirect light, it has more to do with direct light as its name suggests. According to NVIDIA, Imagine adding millions of dynamic lights to gaming environments without having to worry about performance impact or resource constraints. RTXDI makes it possible, and in real time.
Thanks to this technology, geometry of any shape can now be able to emit light and cast shadows appropriately: from tiny LEDs to neon billboards, and even huge fireballs, they will now generate suitable light effects in terms of size. , intensity, bounces, shapes and shadows and also in real time and, again, without a direct impact on the performance of the scene.
According to NVIDIA, without RTX technology even the most powerful GPUs on the market are only capable of creating ray tracing and its shadows for a limited number of sources: typically 2 to 16 of the most important lights in AAA titles or up to 100 lights in games like Quake RTX or Minecraft RTX. Thanks to NVIDIA RTXDI technology, we would be talking about not only being able to generate million points of light, each with its reflections, intensity, shadows and others, but also these lights can be dynamic, be in motion and they will also have a suitable geometry, all without implying an impact on performance.
As you can see, both RTXDI and RTXGI are technologies that help improve lighting effects to make them more realistic, both in shape, size and in the shadows and reflections they generate, increasing the number of these that can be integrated into the scenes and all without impacting performance. Of course, all are advantages.