GART: Games and Applications using RayTracing

[trinibwoy]

For the Nth bounce lag is much less noticeable then for the first

I'm referring to dynamic occluders of the first bounce.

If this door would close / open in an instant, the lag becomes noticeable

Seems we're saying the same thing.

This Metro edition will be really interesting. They're promising a lot. I'm mainly going to be interested in performance at 1080p and 1440p to see where the bottlenecks are.

I really appreciate how they've put fully real-time and fully dynamic lighting firmly in their sights. I was expecting them to push the envelope on their next game but going back and updating Exodus is a huge and welcome surprise.

 

[Scott_Arm]

Also curious about graphics options. For example I’m assuming you won’t be able to turn dxr reflections off because you won’t have cube maps or ssr to fall back to.

 

[manux]

I wonder if ray tracing would scale better to multigpu than traditional rasterization? Could ray tracing heavy engines lead to sli becoming useful again? And completely off topic, could this be the angle amd is potentially taking on when going towards chiplet gpu's? Maybe rasterization isn't as chiplet friendly as one would want but ray tracing could be a game changer there?

 

[Malo]

Also curious about graphics options. For example I’m assuming you won’t be able to turn dxr reflections off because you won’t have cube maps or ssr to fall back to.

Why wouldn't they? It doesn't have reflections in the existing version?

 

[Scott_Arm]

Why wouldn't they? It doesn't have reflections in the existing version?

This new edition is DXR only. It's basically a ray-traced renderer so they can fully optimize for ray tracing. I don't see why it would have fallbacks for everything. I'm really curious to see what can be turned completely off.

 

[trinibwoy]

Why wouldn't they? It doesn't have reflections in the existing version?

The enhanced version apparently isn't directly based on the existing version. So no guarantee that all of its features will carry over.

This upgrade is so extensive, it will require a Ray Tracing capable GPU as the minimum spec, and we will need to deliver this version as a separate product – it is not a simple ‘patch’ to the base game – instead it will be offered as an extra entitlement to all existing Metro Exodus PC players.

I wonder if ray tracing would scale better to multigpu than traditional rasterization? Could ray tracing heavy engines lead to sli becoming useful again? And completely off topic, could this be the angle amd is potentially taking on when going towards chiplet gpu's? Maybe rasterization isn't as chiplet friendly as one would want but ray tracing could be a game changer there?

In a fully raytraced future yes multi-gpu will scale very well in tiled mode. However today's ray-traced games are still dealing with lots of intermediate state that would need to be co-ordinated across multiple gpus (gbuffers, shadow maps, AO).

 

[DegustatoR]

This new edition is DXR only. It's basically a ray-traced renderer so they can fully optimize for ray tracing. I don't see why it would have fallbacks for everything. I'm really curious to see what can be turned completely off.

Actually RT reflections seem to be PC exclusive which means that the game will probably still use SSR on consoles which means that it should be present in PC version too.
Lighting (GI, AO) is the main part which is likely to be RT only.

 

[manux]

In a fully raytraced future yes multi-gpu will scale very well in tiled mode. However today's ray-traced games are still dealing with lots of intermediate state that would need to be co-ordinated across multiple gpus (gbuffers, shadow maps, AO).

There could be some middle ground. Maybe the pure ray casting part could already parallelize very well. Cast a ton of rays for gi, reflections etc. Shading part could be less parallel and run on one card only. Though in this case maybe the under utilized card could be used to cast even more rays/do some limited shading work. Or maybe the underutilized card could use heavier higher quality algorithms for noise reduction.

 

[Scott_Arm]

Actually RT reflections seem to be PC exclusive which means that the game will probably still use SSR on consoles which means that it should be present in PC version too.
Lighting (GI, AO) is the main part which is likely to be RT only.

Yah, looks like you're right about RT reflections looking back at the summary. But you get what I'm saying. Most games have settings from high to low with some features being able to be turned off. If this game requires a DXR compatible card, I wonder how many effects you'll be able turn off. We've seen from benchmarks in other games that you might want to pick your poison with ray tracing, just for performance reasons. I wonder how they'll handle it with this one.

 

[manux]

After seeing ray tracing in cp2077 things like these feel like ... not great. Not that it makes the game any worse. It just feels off.

 

[techuse]

After seeing ray tracing in cp2077 things like these feel like ... not great. Not that it makes the game any worse. It just feels off.

View attachment 5290

Personally the fake reflection is not the thing that stands out most to me as jarring.

 

[manux]

Personally the fake reflection is not the thing that stands out most to me as jarring.

It's worse in movement. Rest stays similarly game like and somewhat believable in gaming context. It's one of those things about ray traced reflections/shadows where effect is more pronounced in movement. Aliasing is because of I used mspaint to scale down. It does piss poor job on scaling images.

 

[HLJ]

After seeing ray tracing in cp2077 things like these feel like ... not great. Not that it makes the game any worse. It just feels off.

View attachment 5290

The Witcher 3 destroyed my suspension of disbelief in other games when it came to foilage.
Cyberpunk 2077 destroyed my suspension of disbelief in other games in regards to lighting and reflections.

The old "what has been seen cannot be unseen" and it is hard to go back in visual fidelity after seeing it done right.

 

[JoeJ]

Seems we're saying the same thing.

Yeah, but you sounded as taking the term 'infinite bounces' as over promising. I see it indeed is, if we wanted all those bounces to be calculated within a single frame, which ofc. isn't possible.
BTW, the first time i saw it was Sonic Ethers Minecraft Mod (which means to me he did not use path tracing but radiosity method, to nit pick). Then came the offical RTX Mod, UE5, and now Exodus. NVs DDGI uses it too, but not sure if there's already a game out using it.
All of them can claim infinite bounces. If somebody claims exactly 5 bounces, we can expect there is no caching, less lag, but much more runtime cost.

 

[Dictator]

Regarding some of the temporal lag from surface caching - it should be very interesting to see what happens in metro and how they discard previous frame lighting from surface caching. One of the neat things they did back when the Two Colonels DLC came out was that they adjusted the denoiser to be able to differentiate between lighting types. As before, with their previous denoiser it would accumulate long, but with ephemeral emmisive surfaces like flames, that would cause trails and glow and ghosts... so they had to massively change the denoiser to support quickly existing and then disappearing emmsive surfaces. I wonder if that "adapative" idea has somehow been integrated into how they surface cache, so as to go around the usual problems of quickly changing lighting conditions.

 

[JoeJ]

The most obvious artifact to me is 'detached shadows'. If you move a box over the floor, the shadow under the box keeps sticking at the floor for some time, and we get a case where lag really looks off.

Traditionally, radiosity caching methods did not use progressive RT. Instead they update the whole incoming light of a patch in one go (can still use RT to resolve visibility, but it's not progressive then.)
Progressive RT adds another source of lag here, making things and inner workings harder to comprehend as well.

 

[manux]

The Witcher 3 destroyed my suspension of disbelief in other games when it came to foilage.
Cyberpunk 2077 destroyed my suspension of disbelief in other games in regards to lighting and reflections.

The old "what has been seen cannot be unseen" and it is hard to go back in visual fidelity after seeing it done right.

Completely agree on this. For me it's specifically seen in motion when gaming. Static pictures or even video tells only so much. Moving the viewpoint and the world reacting appropriately is profound effect. Something about eye hand coordination and brain probably.

 

[OlegSH]

I wonder if that "adapative" idea has somehow been integrated into how they surface cache, so as to go around the usual problems of quickly changing lighting conditions.

"Adaptive" denoising is a thing to the temporal accumulation rescue.
I remember when Minecraft RTX had just came out there was quite noticeable ghosting lag from removing torches in night scenes.
Then they had changed something and the issue had gone.
Probably they reset history in denoiser for such sudden and global lighting changes.
I guess any denoiser should evaluate the difference between the current frame and previous and if the difference is large enought it would be nice to reset history at least for the affected parts of the image.
Using exponential moving average for accumulation should also help prioritizing more recent samples in history. And throwing more rays in disoccluded regions should naturally help with resolving regions not available in history.

 

[Deleted member 2197]

February 14, 2021

 

[Deleted member 2197]