Finally, Metro Exodus has arrived, and so too has another opportunity to see what all the fuss is about in terms of raytracing. Metro Exodus uses a totally different form of raytracing to the reflections seen in Battlefield V. 4A Games instead chose to focus on ray-traced global illumination. Global illumination isn't new to gaming, but it is new in its ray-traced form.
Traditional game lighting uses fixed light sources with direct illumination. Put a lamp in a room and it'll light it up, and it'll also cause a shadow to be cast behind a table, for example. However, direct illumination fails to account for how light reacts in reality. It bends and distorts, reflects and pools. The light cast on a polished table would illuminate a room more than a dirty one. There are techniques used to present global illumination in games in a cheat sheet form used rasterized techniques, but this isn't true global illumination.
Metro Exodus uses ray-traced global illumination, meaning both direct and indirect lighting is rendered in real-time. In theory, this means more natural-looking environments. The tech requires a GeForce RTX graphics cards and there are two different options - High and Ultra. However, certain graphics cards are locked out of certain settings when enabling ray-tracing. Our PNY GeForce RTX 2060, for example, can do Ultra ray-tracing but is restricted to 'High' in terms of overall graphical quality.
It's understandable why 4A Games has done this, as the RTX 2060 probably just can't handle it, although it is a little frustrating not to be able to test these higher settings.
In addition to RTGI, Metro Exodus also uses DLSS (Deep Learning Super Sampling). This is machine learning-based upsampling that reduces image quality but can gain significant performance.
Ray Tracing and DLSS Benchmarks for Metro Exodus performed on a PNY GeForce RTX 2060 6GB XLR8 Graphics Card, Intel Core i7-5820K CPU and 16GB DDR4 RAM
For our benchmarks, we tested how the GeForce RTX 2060 performs while ray-tracing at 1080p and 1440p, with DLSS on and off, and how this compares to the base frame rates.
As we found in our Metro Exodus PC Performance Breakdown and Most Important Graphics Options, ray-tracing typically commands a 33% performance hit to Metro Exodus. This stays largely true across most resolutions. DLSS goes some way to claw some of this performance, albeit at a fairly large and noticeable hit to image clarity. When I saw noticeable, I mean it. DLSS muddies the image in Metro Exodus significantly. That's the trade-off that may need to be made if you want to enjoy higher frame rates with ray-traced global illumination enabled.
If you want to see just what effect DLSS has an image quality, take a look at the sliders below.
Metro Exodus DLSS On vs Off Comparison
Slide your cursor over the image to compare
As you can see, despite the small size of the images you can see a noticeable in resolution quality when comparing DLSS On and Off. This effect is even more noticeable during gameplay. We'd probably recommend you take a straight resolution hit rather than enabling DLSS as at least then you'll know what you're getting. Hopefully, 4A Games can continue to do some work on this feature and improve the overall quality of it.