Metro Exodus: Sam's Story. Ray Tracing with and without screenshot comparisons. Sash Opinion on RTX.
Updated: Mar 16, 2020
After playing with Ray Tracing in Metro Exodus for the second time (the first time was with my RTX 2060 SUPER, now I am playing with it again with an RTX 2070 Non-SUPER, don't ask) I decided to make an updated conclusion to my original thoughts and conclusion regarding the graphics technology in this game, which uses it for certain lights and Global Illumination.
I took some screenshots with Ray Tracing enabled and disabled, in the exact same scene/frame for visual comparisons, but before we look at those, I'll make my updated conclusion clear:
Ray Tracing in Metro Exodus (Sam's Story) is used for Global Illumination and typically varies between being completely unnoticable, to slight differences that don't really look better to huge differences that drastically improve visual quality by increased lighting accuracy and realism. So it is highly dependant on the scene in question, what lights are present and what objects are visible. However, overall, I feel it is something I would definitely keep enabled and I am overall positive about it going forward as the hardware catches up and the performance penalty and cost (hopefully) decreases.
With that out of the way, I will show some comparison screenshots to show what I mean, I'll start with the scenes that didn't really have any visual gain from what I can see.
The game is running on Ultra quality, with Ultra RTX enabled (and disabled for comparison). The resolution is 1920x1080.
Ultra Ray Tracing uses 1 Ray Per Pixel. At 1080p, there are ~2 million rays being traced.
Comparison 1 - No major difference, except a lower frame rate
In this scene the Ray Tracing makes little impact to the image. There are few bits to point out, such as the apartment building on the right and the ship leaning on the centre-left of the image - the plank in front of that ship and its deck are slightly different with Ray Tracing enabled, as they are lit more accurately, but the pretty substantial reduction in Frame Rate (-23%) makes it hard to justify these differences.
Metro Exodus's raster-based Global Illumination technique is very advanced, and handles this scene very well, with higher performance than the Path-traced illumination provided by DXR.
Here is an animated GIF comparison that really shows what is changing in the lighting. That said, without seeing it side-by-side like this, I really didn't notice the difference in this scene when actually playing the game.
Comparison 2 - Noticable differences, but not necessarily 'better looking' even if more 'accurate'.
Looking at this scene, we again (obviously) see a pretty large performance hit for the Ray Traced Global Illumination, but there are some more distinct differences. Firstly, as in the original image the ship in the distance appears to be more accurately lit with Ray Tracing. Secondly, the decking and bed seem to be more illuminated. The fallen wooden pole on the right side of the image is darker with the Ray Tracing. I don't think this scene looks better with Ray Tracing enabled, but it is definitely more accurate.
Judge for yourself with the animated GIF Comparison.
Comparison 3 - Getting better.
Okay, in this scene there are some major differences I definitely notice. If you look at the apartment building in the background, the same building as in Comparison 1. It it is light more realistically with the Ray Tracing enabled. There is more distinction between the shadowed and illuminated parts of the building and generally looks a lot better with RT on in my opinion.
Secondly, the stairwell on the ruin to the right of the scene is darker, and the shadows have more 'depth'. You can notice around the outside of the ruin, where the wallpaper is peeling off, the wall is generally lighter with Ray Tracing. The plank leading to the stairwell looks lighter too.
Here is the GIF comparison.
Comparison 4 - Darker areas are more realistic
Ever since I played with the Ray Traced global illumination in Metro Exodus, I was pretty certain that darker areas of the game benefited the most from the more accurate level of lighting. This comparison underscores that point, the primary area here is the under-side of the wooden roof. You can see it is much more accurately lit (or not lit in this case) with Ray Tracing enabled, and the shadows have a lot of depth. This is accurately simulated lighting that would be very difficult to implement (though not impossible) with normal rasterisation techniques. This really adds immersion and helps with the atmosphere of the game in my opinion.
Here is the GIF Comparison
Here you can really see the depth to the shadows the the Path Traced lighting effects have. While some might argue this is too subtle for the FPS reduction (you can see that in the top left), I actually think this is worth it, even on my RTX 2070. The card is overclocked using 'OC Scanner' to around 2 GHz, and the game is at 1080p, the performance may not be as high as some would like, but your mileage may vary. For a 'cinematic' story experience like Metro Exodus, I think this is worth it.
Of course, RTX 2070 is far from the most powerful DXR capable GPU available, but it's also one of the more cost-effective ones. Overall, I am excited to see how the technology advances and honestly, as the hardware gets more powerful (and cheaper) I think it will really take off.
Think of it this way, future GPUs could add that realistic lighting with no performance penalty. Then, there's really nothing to argue against if the pricing of the product is reasonable. Turing is the pioneer of RT in video games, and comes with the early adopter tax of less than ideal performance.
That said, I have no regrets getting an RTX 2070 over the equally priced RX 5700 XT, because I can actually notice this technology in a game I have hundreds of hours in. But I think for more mainstream acceptance, AMD needs to get onboard an