Digital Foundry Article Technical Discussion [2024]

[troyan]

So there’s no RT shadows aside from RTXDI? Then this blurb from Nvidia doesn’t make sense.

As part of our collaboration, Star Wars™ Outlaws on PC is also being enhanced with NVIDIA RTX Dynamic Illumination (RTXDI), which complements the game’s ray-traced reflections, ray-traced shadows, and ray-traced global illumination, taking visuals to the next level.

I hope RTXDI catches on. The lack of shadows from most lights is a glaring issue in modern gaming. We just got used to it. Time to move on. The DF video highlighted another benefit that isn’t discussed as much. A bunch more lights actually cast light too especially area lights which aren’t raster friendly.

I only played a few hours but there are shadows from direct lights indoors. But these are hard (sharp) and not really realistic.

 

[Shifty Geezer]

The RT solution in the game is a 2 bounce solution, it's possible that statue is too deep inside the cave to be affected by the 2 bounce solution, it could need more bounces. It's possible.

Two bounces will be enough to record occlusion shadowing. You don't need to see a light source. The amount of light energy in the cave will be less but highlights and shadows is all about the delta between surfaces. If you expose for the statue, the surrounds will be shadowed relative to the light that's present no matter how little that might be. the only way I think it'd break is if you have no source lights and just use a flat ambient term on the cave to approximate, at which point the rays will be tracing a uniform 'light source' from every direction.

Left is RT on, right is off, open in new tap for a bigger picture or just click on the pictures and press the arrow keys to quickly move through them and compare.

The problem here is the way the direct light is being represented. It's just got less energy in the RTOff version. The amount of secondary light doesn't seem much different.

2nd comparison: more bounce light on the character and every rock, tree, grass on the ground to his left and on the mountain.

This is much better. Particularly the underside of the rock nook.

3rd comparison: more bounce light on the building in the distance,

Under the eaves is certainly different. I don't understand why the RTX version is more saturated and higher contrast though. I guess something along the lines of the resolve is based on RT lighting and more energy, and the lower energy version is using the same settings or certainly not optimised.

In short, I think there's an art aspect also at work here. Contrast, brightness and saturation shouldn't be affected by light model. Is this difference common between UE5's different lighting modes?

 

[trinibwoy]

The RT solution in the game is a 2 bounce solution

Is there a source for this? Massive described the GI solution in Avatar as a mix of screen space software rays, world space hardware rays and hardware raytraced probes for bounce accumulation. Haven’t seen any indication Outlaws is different.

So the process is to do a screen-space trace. If we hit something, do the lighting of that hit, if we didn't, let's continue from that with a hardware ray into the ray tracing world. Depending on the effect, which is either diffuse GI or specular reflections, the length of the ray is different. So, if it didn't hit anything at the length of the ray, we fall back to the probe result. So we get result from probes on the failure. If you do hit something, we light it with our local lights, sunlight, and also feedback from probes. The probes are both a fallback for missed rays and a source of a secondary light. This is how we get feedback and multibounce.

So, for The Division, we had the probe-based lighting, and this is continued now where we are using it as sort of a cache for the secondary bounces, screen-space GI and ray tracing. Of course we're also taking advantage of hardware ray tracing. But also one of the things that I think we should mention is that we also have a compute shader fallback for this, for graphics cards that don't support hardware-accelerated RT.

It's a bit hard to distinguish between screen-space and world-space rays, because I tend to call world-space rays "hardware rays", but these are also possible to do in software and when we're talking about probes I'd like to emphasise that these are real-time ray-traced probes. There is nothing baked.

 

[DavidGraham]

it's just at a higher exposure. You can tell by comparing the direct illumination of the fire - which you seem to have interpreted as GI

It's more direct illumination, the distant trees are affected more by the light of the fire.

The problem here is the way the direct light is being represented. It's just got less energy in the RTOff version.

Yes exactly, remember the full ray tracing in the game is direct illumination (RTXDI) + global illumination (Lumen + ReSTIR).

The RT image is superior here. Note that unlike the videos you linked earlier there is actual indirect occlusion in the shadowed regions

Here is the comparison we debated so much about, I think the bounce over rocks/center tree/distant cliffs is clear as day. Switch between the two images and the difference will become clear as the 2nd comparison. I am watching this on a 65 inch TV by the way, I can spot small differences easily.

though is is it worth the performance hit for what I think many people would consider fairly minor differences

This isn't relevant to current image quality discussion, but remember the hit in performance is due to direct illumination + global illumination + reflections + shadows + particles reflections + caustics. Not due to illumination alone.

Is there a source for this? Massive described the GI solution in Avatar as a mix of screen space software rays, world space hardware rays and hardware raytraced probes for bounce accumulation. Haven’t seen any indication Outlaws is different

We are talking about Black Myth Wukong, not Outlaws.

 

[trinibwoy]

We are talking about Black Myth Wukong, not Outlaws.

Ah my bad.

 

[Charlietus]

I'm still skeptical that this is actually 5.0. Is this based on anything other than binary metadata yet? Someone could probably get a better estimate by trying some cvars that were added in 5.1, 5.2, etc. and seeing which are present. I think some of the Unreal tools that enable the console or similar could probably dump the full list for cross referencing. Or you know, someone could ask the developers

Aside from the metadata, TSR on PC doesn't look much better than FSR 2 here, and we know it had many quality upgrades with newer versions. It also doesn't use nanite for foliage. But admittedly, there is no "hard" evidence.

 

[Charlietus]

I'm still skeptical that this is actually 5.0. Is this based on anything other than binary metadata yet? Someone could probably get a better estimate by trying some cvars that were added in 5.1, 5.2, etc. and seeing which are present. I think some of the Unreal tools that enable the console or similar could probably dump the full list for cross referencing. Or you know, someone could ask the developers

Oops, double message

 

[Dictator]

So there’s no RT shadows aside from RTXDI? Then this blurb from Nvidia doesn’t make sense.

As part of our collaboration, Star Wars™ Outlaws on PC is also being enhanced with NVIDIA RTX Dynamic Illumination (RTXDI), which complements the game’s ray-traced reflections, ray-traced shadows, and ray-traced global illumination, taking visuals to the next level.

I hope RTXDI catches on. The lack of shadows from most lights is a glaring issue in modern gaming. We just got used to it. Time to move on. The DF video highlighted another benefit that isn’t discussed as much. A bunch more lights actually cast light too especially area lights which aren’t raster friendly.

The RT shadows without RTXDI are for extremely distant large objects, Like boulders, cliffs, etc. I am Not Sure Ifanyone remembery, but they described it in their presentations and in our Interview with them.

 

[trinibwoy]

The RT shadows without RTXDI are for extremely distant large objects, Like boulders, cliffs, etc. I am Not Sure Ifanyone remembery, but they described it in their presentations and in our Interview with them.

Got it. They’ve got a lot of different real time lighting systems working at once. Impressive but must be a lot of overhead to maintain.

If they’re running high resolution BVHs for RTXDI anyway I wonder why they didn’t upgrade the RT reflections to use the same high quality geometry. Could’ve hidden it behind the outlaw setting if it’s too heavy.

 

[Andrew Lauritzen]

Here is the comparison we debated so much about, I think the bounce over rocks/center tree/distant cliffs is clear as day. Switch between the two images and the difference will become clear as the 2nd comparison. I am watching this on a 65 inch TV by the way, I can spot small differences easily.

Right, and that comparison very clearly shows what I am saying. You keep saying things like I can't "see the difference". Of course I can see the difference, I look at much smaller pixel differences every day for a job. My point is that the "RT" version in the PC-cine shots is just uniformly more lit/exposed in the shadows. It's as if there's a constant ambient/skylight term, not real path tracing (or even any real GI) which would vary far more and have indirect shadows. The second shot is more debatable but the PC-cine shot is either broken or the GI is spending a whole lot of cycles to accomplish the same thing as adding a constant value to all the shadowed pixels like it's early 2000's.

This isn't relevant to current image quality discussion, but remember the hit in performance is due to direct illumination + global illumination + reflections + shadows + particles reflections + caustics. Not due to illumination alone.

Of course but I'm talking about the performance when only direct and indirect illumination is onscreen. I'd be more willing to accept it if it only dropped when there was significant reflections, caustics, etc. onscreen but the performance hit is across the board. In a practical sense it's just not a very usable mode right now, but hopefully will become so in the future with faster hardware.

 

[Shifty Geezer]

To be fair, in that environment GI probably would just look like a constant ambient term. You're getting sandy-rocky bounce light from every direction.

 

[DavidGraham]

the PC-cine shot is either broken or the GI is spending a whole lot of cycles to accomplish the same thing as adding a constant value to all the shadowed pixels like it's early 2000's

We all know you can fake global illumination easily, nothing new here, Mirror's Edge did it in a spectacular manner in 2008 on Unreal Engine 3, but you have to bake a ton of things, and it wouldn't be dynamic. Maybe the ReSTIR + Lumen system in Black Myth is burning lots of cycles doing the same indeed (but in a dynamic manner), or maybe the scene composition is set up that way.

Have a look at the top of the cliff there, it clearly has bounce light in the ray traced shot, with ray tracing off it's completely dark. This doesn't look like a uniform ambient term at all.

In a practical sense it's just not a very usable mode right now

Preferences vary, on a 3080, I can do 1440p DLSS Performance at max settings and 30fps, it's a console like experience, but I don't mind that if I am going to enjoy max visuals.

To be fair, in that environment GI probably would just look like a constant ambient term. You're getting sandy-rocky bounce light from every direction.

Yep.

 

[Dictator]

Got it. They’ve got a lot of different real time lighting systems working at once. Impressive but must be a lot of overhead to maintain.

If they’re running high resolution BVHs for RTXDI anyway I wonder why they didn’t upgrade the RT reflections to use the same high quality geometry. Could’ve hidden it behind the outlaw setting if it’s too heavy.

Yeah I wonder why not too - especislly since they have a separate BVH Option and all that.

 

[Andrew Lauritzen]

To be fair, in that environment GI probably would just look like a constant ambient term. You're getting sandy-rocky bounce light from every direction.

Color bleed is not the only - or even primary - hallmark of GI. The main telltale here is it's missing obvious local occlusion from the dead trees and crevasses in the rock. Stuff that even GTAO or other screen space methods would pick up. Shading should also be biased towards the primary directions of light bounce (i.e. more downwards or sideways).

Anyways I'll repeat that it's kind of impossible to judge from just these screenshots between whether something is broken or if it's working but is just not very impressive GI in those instances. Since the GI looks better in other cases I'm still guessing broken, but either way it's producing a result that is missing a lot of important features in the indirectly lit areas, for whatever reason.

To be clear I have no major quality complaints about the RT path when I've run it locally (only performance...), I'm speaking to those specific comparisons/videos.

 

[Frenetic Pony]

SW Outlaws is easily the most I've enjoyed looking at a game in years. Enormous Star Wars vistas, RT sun shadows that are somehow performant even on overactive foliage, multibounce GI that ok looks a little flat sometimes but is often stunning and doesn't suffer any overdarkening anywhere, just a fantastic job all around.

I did try to take a screenshot in photo mode, but the jpeg doesn't come out right from HDR inputs. Ohwell, maybe if the US Justice Department bootstomps Google enough we can finally have nice things on the internet again like JpegXL support.

 

[XboxKING]

Preferences vary, on a 3080, I can do 1440p DLSS Performance at max settings and 30fps, it's a console like experience, but I don't mind that if I am going to enjoy max visuals.

Sounds like you are merely moments away of getting a steam deck and running PS3 equivalent visuals

 

[Bludd]

DF Direct Weekly #178: PS5 Pro Incoming? Black Myth: Wukong Xbox, MGS Delta/Silent Hill 2 Hands-On!​

0:00:00 Introduction
0:01:07 News 1: PS5 Pro name, design possibly leaked
0:27:16 News 2: Why isn’t Black Myth: Wukong on Xbox?
0:41:24 News 3: Astro Bot VR ruled out - but PC could be coming
0:49:53 News 4: MGS Delta: Snake Eater preview!
1:06:53 News 5: Silent Hill 2 hands-on!
1:26:24 News 6: Avowed vows to target 30fps on Xbox Series consoles
1:34:48 Supporter Q1: What games do you most want to see updated for PS5 Pro?
1:41:36 Supporter Q2: How will Microsoft deal with the PS5 Pro?
1:52:24 Supporter Q3: Could Intel GPUs be in the next-gen consoles?
1:56:35 Supporter Q4: Given that the 4090 can no longer sustain native 4K at max settings in a lot of games, are we about to hit a performance wall?
2:04:28 Supporter Q5: Did Sony and Microsoft underestimate the needed console specs this generation?
2:12:19 Supporter Q6: Would DF consider adding a quantitative rating system to their reviews?

 

[Shortbread]

*Ignore*

 

[Frenetic Pony]

How much better or how noticeable multiple light bounces are in a game is subjective to scene and art. A different view is the practical needs of devs, you can see this hour long playthrough of Avowed just how much lighting artists need to "work around" UE5's limited light bounces, literally needing to come up with multiple types of new light sources just to get interiors viewable at all despite multiple places in the level letting in sky and sunlight. With say, 4 light bounces instead of 2 w/feedback there'd be less need to place to extra light sources all over.

 

[Charlietus]

How much better or how noticeable multiple light bounces are in a game is subjective to scene and art. A different view is the practical needs of devs, you can see this hour long playthrough of Avowed just how much lighting artists need to "work around" UE5's limited light bounces, literally needing to come up with multiple types of new light sources just to get interiors viewable at all despite multiple places in the level letting in sky and sunlight:

That's something that bugs me about this. It's a big problem in wukong. Some parts of the maps are just pitch black, I really don't like how it looks.

Did wukong really need to use lumen? It's a (mostly) linear game with no time of day transitions. Naughty dog games have really good bounce lightning with no visibility problems, with dynamic objects being the only negative.

I'd say that baked lighting still has it's place for those types of games.

By the way, isn't lumen supposed to be infinite bounces? Or are black spots causes by something else?

PS: I just learned that avowed will have a day to night cycle, so what I said doesn't apply.