Next gen lighting technologies - voxelised, traced, and everything else *spawn*

[Dictator]

My video is going up on this tomorrow - as well as two interviews with the developers about the game engine and the ray tracing implementation.

As to why DXR being off looks so "bad" in some scenes when you direct comparison, you have to contextualise what the game is and what it is doing. It has a real-time time of day and very very large levels. So no baking out lightmaps... Games that rely on real-time methods tend to generally look pretty bad in overhanging areas in shadow to be honest. It is the part modern game rendering that generally looks very flat and floaty and where lighting has very incorrect local directionality usually.
Also, the basic GI as found in non-raytraced versions of Metro Exodus is actually not technically incompetent as some are suggesting here. You can read about it and more the interviews we will have.

 

[Ike Turner]

My video is going up on this tomorrow - as well as two interviews with the developers about the game engine and the ray tracing implementation.

As to why DXR being off looks so "bad" in some scenes when you direct comparison, you have to contextualise what the game is and what it is doing. It has a real-time time of day and very very large levels. So no baking out lightmaps... Games that rely on real-time methods tend to generally look pretty bad in overhanging areas in shadow to be honest. It is the part modern game rendering that generally looks very flat and floaty and where lighting has very incorrect local directionality usually.
Also, the basic GI as found in non-raytraced versions of Metro Exodus is actually not technically incompetent as some are suggesting here. You can read about it and more the interviews we will have.

?? I wonder what magical solutions, that doesn't involve RT, all other open word games with ToD (RDR2, ACs, etc) are using which doesn't make them look like utter crap (like Metro which doesn't look great with RT either as seen above..)..

 

[London Geezer]

?? I wonder what magical solutions, that doesn't involve RT, all other open word games with ToD (RDR2, ACs, etc) are using which doesn't make them look like utter crap (like Metro which doesn't look great with RT either as seen above..)..

Secret sauce. Must be.

 

[Shifty Geezer]

Maybe some reference images of alternative games would be better than just saying they exist? Are there any ToD games with better interiors that people can link to?

 

[Dictator]

?? I wonder what magical solutions...

I actually pointed out an area in red dead redemption 2, of which there actually many you can find, that suffered from the exact same "lacks good indirect lighting in a shadowed overhang" in a video of mine. Here with time code.

Screengrab from higher bitrate version of video, RDR2:

^^ plain grey directionaless lighting in an overhang shadow


I think it would be reasonable to say that many of these games with similar constraints have this issue actually if you look at them, yes these open world ones.

To emphasise it since people seem to have an odd impression I think - just because you have seen bad areas of lighting with traditional GI Metro uses in comparison to the RT implementation, does not mean it looks completely terrible everywhere or something. Here, the traditional GI looking pretty alright if you ask me:
Standard GI

RT GI

 

[Ike Turner]

I actually pointed out an area in red dead redemption 2, of which there actually many you can find, that suffered from the exact same "lacks good indirect lighting in a shadowed overhang" in a video of mine. Here with time code.
I think it would be reasonable to say that many of these games with similar constraints have this issue actually if you look at them, yes these open world ones.

To emphasise it since people seem to have an odd impression I think - just because you have seen bad areas of lighting with traditional GI Metro uses in comparison to the RT implementation, does not mean it looks completely terrible everywhere or something. Here, the traditional GI looking pretty alright if you ask me:
Standard GI

RT GI

No one is saying that baked GI doesn't have issues (via light probes or volumes which is what 95% games with ToD use). The issue is that Metro looks exceptionally bad in some cases and where the lighting with RTX Off doesn't make any sense at all compared to RTX On (there shouldn't be any difference between On/OFF in interiors where there's no sunlight coming in, no? Isn't the sun the only source of lighting for RT in the game?). Their SSAO solution is also ridiculously bad for some reason.

 

[Dictator]

No one is saying that baked GI doesn't have issues (via light probes or volumes which is what 95% games with ToD use). The issue is that Metro looks exceptionally bad in some cases and where the lighting with RTX Off doesn't make any sense at all compared to RTX On (there shouldn't be any difference between On/OFF in interiors where there's no sunlight coming in, no? Isn't the sun the only source of lighting for RT in the game?). Their SSAO solution is also ridiculously bad for some reason.

Which interiors do you mean?

With regards to the SSAO, I am not sure why you say it is ridiculously bad? It looks like it is doing that standard SSAO thing where it grounds object contact points with a small halo like shadow, seems to be working as intended in my play through.

 

[DavidGraham]

Things like no contact shadows on sleeves and faces that aren't lit properly and whatnot that still plague these RTX games.

All the train scenes are amazing, the trains and their passengers are dynamically lit with indirect lighting from the sun and snow, and they are all moving. That's a breakthrough right there in my books, dynamic GI affecting moving objects.

 

[Scott_Arm]

I honestly don't get it. The comparison images between rtx off and rtx on show significant improvement. Whether it's worth the performance difference is completely subjective, but I don't know how anyone can look at the images provided in those benchmark links and not be able to see the differences when directly comparing.

There is some truth to, "You wouldn't know the difference if you weren't doing a direct comparison." All of the underlying assets, like the models and textures are the same. Videogames have also gotten pretty good at faking lighting. There's no doubt. We're also very used to the way games look. That said, looking at the RTX images, it's quite obvious they're the ones that look massively better.

 

[Scott_Arm]

You can't expect that to happen in every scene, light cheats abd static GI is very well made in the game You also don't focus on the scenes that don't work and ignore those that show a huge difference . Most outdoor areas show a significant improvement, that alone is enough to showcase the tech.

I like the comparisons of nearly pitch black rooms and hallways with no sunlight that look pretty much the same. There's no GI from sources other than the sun, so all you get is differences in AO, but the room is almost pitch black so ...

 

[vipa899]

My video is going up on this tomorrow - as well as two interviews with the developers about the game engine and the ray tracing implementation.

As to why DXR being off looks so "bad" in some scenes when you direct comparison, you have to contextualise what the game is and what it is doing. It has a real-time time of day and very very large levels. So no baking out lightmaps... Games that rely on real-time methods tend to generally look pretty bad in overhanging areas in shadow to be honest. It is the part modern game rendering that generally looks very flat and floaty and where lighting has very incorrect local directionality usually.
Also, the basic GI as found in non-raytraced versions of Metro Exodus is actually not technically incompetent as some are suggesting here. You can read about it and more the interviews we will have.

Thanks will read when availeble.

I think it would be reasonable to say that many of these games with similar constraints have this issue actually if you look at them, yes these open world ones.

Agree, one sees what one wants to see. Even the impressive RDR2 can be faulted, though overall its a piece of art, multiplatform also!

 

[DavidGraham]

Hardware Unboxed loved the implementation of RTX in Metro especially that it only costs around 25% of performance at 1440p. And improves lighting all over.

 

[Kaotik]

Hardware Unboxed loved the implementation of RTX in Metro especially that it only costs around 25% of performance at 1440p. And improves lighting all over.

The bolded part sounds funny considering they only use RT for sun + sky light sources

 

[DavidGraham]

The bolded part sounds funny considering they only use RT for sun + sky light sources

RT AO is used for all light sources.

 

[JoeJ]

only use RT for sun + sky light sources

Pretty sure both is combined to a single image based light (with higher probability of rays to take the direction towards sun).
Calling this 'GI' is quite exaggerated. I really see it as an AO showcase.

I wonder why they did not include the flashlight at least. Performance should do, considering flashlight and sun is rarely used at the same time.

Is the stealth gameplay argument the reason?
But no. With that many AO it would be still darker than RTX off, even with bounced flashlight.
Saying they don't want to affect stealth gameplay with RTX, but making it noticeable darker? Really a bad excuse to me.
Performance limit is more likely, but makes no sense to me either.

 

[milk]

Pretty sure both is combined to a single image based light (with higher probability of rays to take the direction towards sun).
Calling this 'GI' is quite exaggerated. I really see it as an AO showcase.

I wonder why they did not include the flashlight at least. Performance should do, considering flashlight and sun is rarely used at the same time.

Is the stealth gameplay argument the reason?
But no. With that many AO it would be still darker than RTX off, even with bounced flashlight.
Saying they don't want to affect stealth gameplay with RTX, but making it noticeable darker? Really a bad excuse to me.
Performance limit is more likely, but makes no sense to me either.

I think it was just dev-time prioritizing. Have they explained how their implementation works? How do they determine bounces? do they shoot a bunch of rays from every few pixels? How do they determine boucned lighting? Shade on hit? Seems inpossibly costly. Do they use something like Reflective Shadow Maps? That one can explain the "only for sun" limitation. Would fit flashlights well too, like LoU managed on damn PS3, with no RT by the way. Just a bunch of very cheap VPLs.

 

[JoeJ]

I think it was just dev-time prioritizing.

I don't believe this either, but i don't know how it works. My guess about GI is somewhat like this:
For each cluster of pixels (e.g. 3x3) shoot one ray into random direction, shade the intersection as usual, trace one further ray towards random sky direction, denoise similar to Q2.
(There was a short scene in dev video with visible noise. Frequency of noise hints they use not more than 3x3 pixels per ray, more likely one full ray for each pixel maybe)

If it's anyhow like this, to support other lights all you have to do is to randomly switch between sky and those other lights (like Q2). Would not have been much more work. (More noise - but at least for flashlight it should have worked i guess.)
Likely they'll talk at GDC...

I also wonder, with so many people complaining about 'blurry MLAA', why not raytrace at low res, scale RT buffer up and apply to full res raster image? Guess we all expected this but neither BFV nor Metro do this. (Likely the win would be too small or artifacts)
Btw, those people should look at real camera footage. I've worked with footage from very expensive cameras - they are not sharper than MLAA images. I'm disappointed people dislike nice smooth images.

 

[milk]

I also wonder, with so many people complaining about 'blurry MLAA', why not raytrace at low res, scale RT buffer up and apply to full res raster image? Guess we all expected this but neither BFV nor Metro do this. (Likely the win would be too small or artifacts)

Because naive upsampling of low res lighting looks horrible at depth/material discontinuities, and doing it non-naively is the real catch. Albeit hard, it is doable, and seems to be what BFV did, in a way, just with variable resolution across the screen.

http://tuxedolabs.blogspot.com/2017/11/upscaling-half-resolution-screen-space.html

This blog post shows some naive upsampling of pathtraced (in ss) lighting on top of higher res gbuffer. It does not look acceptable.

 

[DavidGraham]

muted difference?

 

[JoeJ]

muted difference?

The problem is they call this 'GI' although it's restricted to a single static light (the sky).
The Tomorrow Children has a much more advanced lighting model including reflections, multiple area lights, soft shadows, multiple bounces (can't remember if it's 2 or 3).
So of course some people are not impressed, considering the term GIobal Illumination by definition includes all of this.

Also, if you show just the RTX screenshots, nobody would be impressed, and nobody would think you need rays to get this. Looks like any other game.
Both GI and AO is a bit of an ungrateful use of RTX, because it's low frequency. Sharp reflections are just more impressive an easier to sell (but not more important IMHO).