GPU Ray Tracing Performance Comparisons [2021-2022]

[DegustatoR]

Enhanced edition has a ton more RT stuff going on than the original metro exodus had.

Besides the additional RT reflections what does it have? "Infinite" bounces? These are temporally accumulated so shouldn't be of a big hit to performance.

 

[manux]

Besides the additional RT reflections what does it have? "Infinite" bounces? These are temporally accumulated so shouldn't be of a big hit to performance.

Too many differences to summarize. Original metro was pretty lacking and some things were only present in dlc. Article below goes to some technical depth on what has changed. There also is more to do.

There is still more to do. Implementing a fully-fledged, real-time, path-traced rendering engine has been a learning experience as much as anything. It has opened up new avenues of development to us. It has highlighted areas where we can still improve in our pursuit of ever increasingly photorealistic imagery. We’re proud of what we have accomplished so far and it will be the inspiration for many new features to come as we move forward with future projects.

Stay tuned for a follow-up blog about how we've integrated these updates specifically into Metro Exodus versions for Xbox Series X | S and PlayStation 5 set to release on June 18!

- The 4A Games Team

https://www.4a-games.com.mt/4a-dna/in-depth-technical-dive-into-metro-exodus-pc-enhanced-edition

 

[DegustatoR]

Too many differences to summarize.

I've just summarized them in my previous post.

 

[Subtlesnake]

Besides the additional RT reflections what does it have? "Infinite" bounces? These are temporally accumulated so shouldn't be of a big hit to performance.

The original GI solution only applied to light cast from a single light source (the Sun), right? And based on that article they now support up to 256 additional light sources per scene.

 

[manux]

I've just summarized them in my previous post.

Reading the blogpost from developer I linked gives a lot more depth than one or two line summaries. It's complicated enough subject with non standard terminology that only knowing summary gives a failing grade in understanding what is going on. The devil really is in details,...

One buzzword can expand to explanation below which still is incomplete in details. It's pretty unlikely in forum like this that everyone would understand buzzwords and know context. It's a good idea to seek expanding understanding and read the developer material to really understand what is going on in specific games. If we don't do this we are no better than monkeys throwing poop at each other.

Originally, we used a single light source for creating these bounce light sources: the sun. It would be fair therefore to suggest that, for every pixel, we had one additional light source contributing to the global illumination. You could maybe say two, if you include sampling the sky texture since the sky is really one large area light source.

We have extended this raytraced lighting pipeline to much more closely resemble the deferred lighting pipeline used for direct illumination of on-screen pixels. We now allow for up to 256 analytic lights sources to contribute to each sample, meaning that for every pixel we can now have up to 256 light sources, in addition to the sun and the sky, all adding information to the RTGI term. These can all be spot or radial lights, each with their own shadow map to provide accurate secondary occlusion. They use the N-dot-L equation plus inverse square falloff to determine intensity, but that really is accurate enough for these indirect, diffuse situations. As an optimisation, to help cull as many lights as possible in areas where they have no effect, we partition our scenes using a world-space grid. In each grid cell (called a cluster), we simply list all of the light that are in range and might affect geometry in that location. This system is almost identical to the screen-space light clustering system we use for culling lights in our deferred renderer except that we divide up the game world rather than the screen.

 

[DegustatoR]

Reading the blogpost from developer I linked gives a lot more depth than one or two line summaries. It's complicated enough subject with non standard terminology that summary gives a failing grade in understanding what is going on. The devil really is in details,...

One buzzword can expand to explanation below which still is incomplete in details. It's pretty unlikely in forum like this that everyone would understand buzzwords and know context. It's a good idea to seek expanding understanding and read the developer material to really understand what is going on in specific games. If we don't do this we are no better than monkeys throwing poop at each other.

Local lights were added into GI calculations in the original version with the release of Two Colonels DLC, it's not exactly new or exclusive to EE version of the game.
As I've said, beyond the addition of RT reflections and the temporal accumulation of bounces to make GI better there's not a lot which is new in EE's RT when compared to the original release.
And while it is impressive that it's performance is about the same despite the huge gain in IQ it's not some unimaginable achievement considering the extent of RT changes between the original and EE versions.
Again, highlights the fact that devs got a lot smarter in how they use RT h/w over these couple of years.

 

[manux]

Local lights were added into GI calculations in the original version with the release of Two Colonels DLC, it's not exactly new or exclusive to EE version of the game.
As I've said, beyond the addition of RT reflections and the temporal accumulation of bounces to make GI better there's not a lot which is new in EE's RT when compared to the original release.
And while it is impressive that it's performance is about the same despite the huge gain in IQ it's not some unimaginable achievement considering the extent of RT changes between the original and EE versions.

I'll live it at this. you are claiming apparently enhanced edition is same as two colonels dlc. Developer directly contradicts this. I don't know how to convince you if you are not willing to read what the developer of the game wrote.

 

[DegustatoR]

I'll live it at this. you are claiming apparently enhanced edition is same as two colonels dlc. Developer directly contradicts this. I don't know how to convince you if you are not willing to read what the developer of the game wrote.

I've read that post before you did most probably. What I've gotten from it is above.

 

[T2098]

I'll live it at this. you are claiming apparently enhanced edition is same as two colonels dlc. Developer directly contradicts this. I don't know how to convince you if you are not willing to read what the developer of the game wrote.

DF's video commentary was quite helpful too and goes in depth with visuals on exactly what the new features are.
The important bits are in the first 20 mins, and there are links in the description to skip to exact spots where they discuss each new feature.

 

[Jawed]

I dunno seem to run about the same in my benchmarks, maybe slightly slower.

Have you published your benchmarks? Can you link them?

I'd say that it shows the progress which was made in applying RT to games during the last couple of years - being smarter in how you use RT h/w. The fact that they've dropped non-RT h/w support is not necessarily relevant here.

I wonder how much the very low geometric complexity of ME:EE plays into the "RT hit".

 

[DegustatoR]

Have you published your benchmarks? Can you link them?

I've made them on my own home PC for fun. If you insist:

Metro Exodus
5900X / 3080 @ 465.89 / Win10x64 20H2
Extreme preset + RT Ultra

1920x1080 - 77,54
2560x1600 - 58,12

Metro Exodus Enhanced Edition
5900X / 3080 @ 466.27 / Win10x64 20H2
Extreme preset + RT UItra + RT Reflections

1920x1080 - 75,72
2560x1600 - 54,15

 

[Jawed]

I've made them on my own home PC for fun. If you insist:

Metro Exodus
5900X / 3080 @ 465.89 / Win10x64 20H2
Extreme preset + RT Ultra

1920x1080 - 77,54
2560x1600 - 58,12

Is that in the Two Colonels DLC?

 

[DegustatoR]

Is that in the Two Colonels DLC?

No, it's with the game's built-in benchmarking tool which does a fly-by through a segment of Taiga map. Doing custom hand controlled run-throughs just for fun seems a bit too much work.

 

[OlegSH]

I wonder how much the very low geometric complexity of ME:EE plays into the "RT hit"

Sry, but why don't you just read developers sessions before making the very bold "low geometric complexity" claim which has nothing to do with reality?
Here, please take a read.

In short, 20 millions of polygons is an average number of polygons. I don't know a lot of 2020-21 games which are pushing as much triangles, not even speaking of 2019 games.
They made some obvious optimizations for RT GI by reusing geometry from depth and shadows passes, which doesn't carry UVs since they don't evaluate materials in hit points, so it's faster to process. Also, they don't tessellate since they don't do shadows

As for the hit due to geometry complexity, from my tests in UE5, RT reflections work perfectly well with 100% Nanite proxies unless you go mad and put a few dozens of instances in the same spot, which would obviously increase traversal time dramatically.
You don't need that much of complexity though and even 6% proxies do the job of keepeing geometry's self reflections and self shadowing correct for models I've tried (Epic suggests 1%, but that's too low for geometry with complex shapes), and that's the most problematic place when you simplify geometry for RT (default SDF's are super low res so they are only good for GI and other super diffuse stuff where you can't distinguish the underlying super simple SDF complexity and shading).
Going from a few billions triangles with 100% proxies to 6% proxies with a few million triangles in scene saves 1 millisecond for reflections, so higher geometry complexity slows down performance, but not by much, as expected with the log(o) scaling. Primary rays without any LODs are as fast as the Nanite rendering itself, thought, it's not as efficient for memory usage.

There are still quite a few optimizations left on the table, so they can still accelerate RT by a lot by doing geometry merging, the same stuff they did for global SDF and by doing a number of other things.
Their Lumen cache stuff seems to be quite fragile because even Epic's homemade Quixel models break it with ease, not speaking of the lack of dynamic geometry support, they need something more versatile for GI in the future for sure. As for reflections with roughness < 0.4, HW RT is the only way to go in UE5 because otherwise you would get the mess that the SDFs and the cache is.

 

[Jawed]

In short, 20 millions of polygons is an average number of polygons. I don't know a lot of 2020-21 games which are pushing as much triangles, not even speaking of 2019 games.

Then these are the worst-looking polygons.

Maybe that's 20M triangles after maximum tessellation they're counting?

 

[trinibwoy]

Then these are the worst-looking polygons.

Maybe that's 20M triangles after maximum tessellation they're counting?

Yeah based on the DF video some of the pre-tessellated assets in Exodus are really terrible.

 

[OlegSH]

Then these are the worst-looking polygons.

The same polygons as in Demon Souls, which was praised many times for tesselation.
But I agree, 4A Games could have done better job by highlighting them with dirty cheap and non correct screen space shadows in the same way Blue Point did in Demon Souls since diffuse ambient lightning is not capable of making these details "pop" by alone.

Maybe that's 20M triangles after maximum tessellation they're counting?

On closeups - maybe, but the game is also full of panoramic views with tons of objects in view.

 

[techuse]

Metro Exodus does look low poly. I wonder about the details of that 20 million statement. That's also the typical amount of rendered triangles for the UE5 demos and the perceived polygon difference is huge.

 

[OlegSH]

I wonder about the details of that 20 million statement

"Massive scenes ~150 000 000 triangles on a typical Metro level in TLAS before culling" - right from the presentation I linked above.
Of course only a fraction of that will be in a frame after culling even in the panoramic views I've mentioned above

 

[OlegSH]

Metro Exodus does look low poly

Not agree, sometimes it's for certain assets, but sometimes it looks very high poly. As in all open world games, assets quality swings widely in this game. For some reason, such assets as rocks and mountains are quite low poly in the game and I guess they are to blame for the low poly look, but there are also quite a few very high poly assets.