Digital Foundry Article Technical Discussion [2023]

[VFX_Veteran]

It's quite likely that Avatar does use importance sampling. Importance sampling is a fundamental technique for decreasing noise for any GI implementation and is widely used across all real-time GI implemetions, both older ones like in Metro which people call RTGI and newer ones like in Cyberpunk Overdrive, which people call path tracing.

https://developer.download.nvidia.com/video/gputechconf/gtc/2019/presentation/s9985-exploring-ray-traced-future-in-metro-exodus.pdf

I don't disagree with that but you'd need a lot of samples in order to get a good approximation. Also don't know what the scene looks like geometrically when rays are fired to see what surrounding color contribution is computed for the pixel.

 

[trinibwoy]

At the end of the day all techniques are similar. Some form of importance sampling, ray guiding, ray caching and a denoiser on top. Devil is in the details, which often can be only compared by reading papers and talks, as games have lots of tricks like simplified BVH, simplified materials for ray tracing or emulating GI with manually placed analytical lights, which hide strengths and weaknesses of GI methods.

Yeah, it’s great to see the rapid iteration and innovation in real-time GI. Looks like most devs are still shying away from per-pixel multi-bounce GI and choosing lower resolution alternatives. Will be interesting to see how this generation ends up after all the major engines have shown their stuff.

 

[Dr. Nick]

 

[Jupiter]

While the outdoor areas in Avatar look very good, the lighting of the isolated indoor areas can't even begin to keep up with the pathtracing games. Unlike Cyberpunk 2077, not all light sources cast shadows. If you're used to pathtracing the indoor lighting looks inconsistent. Partly unsightly for me.
Outdoor areas can still be made vivid without pathtracing but RT GI is highly recommended. Even in a non RT GI game like Battlefield 2042 the outdoor areas can look okay. Inside, however, you only see lighting mistakes.

Yah that’s the primary reason I don’t think CP2077 is as visually good as Alan wake 2 or Avatar (in some areas). Cyberpunk just looks kind of simple. It’s very clean with straight lines and not much clutter. The roads are very smooth and weirdly shiny. It looks like ps4 geometry and world detail with amazing lighting. Some npcs and areas look highly detailed and I think the expansion content looks better.

Control has many smooth surfaces and yet it looks fabulous. When I play Control I see a very elaborate render quality that already needs more computing power than the newly released PlayStation 5 can provide. It doesn't remind me of the last console generation at all.

Cyberpunk 2077 has quite a bit of geometry for a game in a city. It also has a lot of different individual objects standing around. Some of them are very detailed (vehicles) and other could be made better (food products) but that doesn't detract much from the overall impression. Cyberpunk 2077 lacks tessellation and therefore the ground is too smooth whereas it is 3D in Avatar.

Overal, Night City is not a last gen world detail for me. The focus was clearly on the PC and when I look at typical open world games from the last console generation they are much less detailed and simpler to create. Spiderman 2 is an exclucive PlayStation 5 game and at close range it looks simplictic to me. The Division has more details but in Spiderman 2 you're not just on the ground either.

In Cyberpunk 2077, many people only have driving and walking around in their heads. The game also has a lot of highly expensive set pieces for the missions. Thanks to pathtracing they look even more impressive now. But I hope that CD Projekt Red will fix the bugs in the glass, integrate smoke into pathtracing, and fix shadowing so that the shadows on water become blurred. Then it would be perfect.

 

[Remij]

Once again I'll say that Oliver always manages to say what I'm thinking in my head while listening to any given DF Direct discussion and always manages to consider and present the wider picture in a clear and concise way when it comes to a lot of subjects. I really appreciate that about him!

DF Directs have got to be one of my favorite things on Youtube!

 

[Shortbread]

It's the last edition of DF Direct Weekly for the year that is 2023, and it kicks off with discussion surrounding Insomniac data hack. What sets this 'leak' apart from others that makes media think twice about publishing stories on it? How does it compare in scale to other leaks? It's a tricky one for sure. Meanwhile, rumours are starting to emerge that Xbox may be considering a 2026 release for its next-gen console, but how viable is that in the context of the information that emerged from the FTC leak? Finally, John reveals the results of his GT7 vs Forza Motorsport in-video quiz, while the DF Supporter Program's community awards are unveiled!

0:00:00 Introduction
0:01:00 News 01: Insomniac hacked
0:19:38 News 02: Valhalla DLC launches for God of War Ragnarök
0:28:02 News 03: PS5 outsells Xbox Series 3 to 1, next Xbox rumored for 2026 launch
0:49:21 News 04: John’s Forza Motorsport vs. GT7 poll results!
0:54:20 News 05: DF Community Awards 2023!
1:06:36 Supporter Q1: Will 2024 be the year RT becomes pervasive?
1:09:11 Supporter Q2: How does Resident Evil 4 on Apple Silicon run?
1:12:01 Supporter Q3: When using an IPS panel, how can you reduce IPS glow?
1:21:29 Supporter Q4: Would John consider doing a DF Retro on fur or grass rendering in games?
1:23:51 Supporter Q5: When path tracing becomes more common in games, what will be left to critique visually?
1:28:54 Supporter Q6: What was your favorited Digital Foundry moment of the year?

 

[Jupiter]

I bought Robocop to broaden my horizons. Then you can look at everything in peace and from every direction. Of the games mentioned by Digital Foundry, I already have Alan Wake 2, Cyberpunk 2077 and Dead Space. Resident Evil 4 will also follow soon.

Robocop can look quite good but it also has significant lighting problems. There are often no shadows and the GI is simple. See the images. I notice such problems in almost all places although there is no dynamic day and night change. Avatar also has such problematic areas in indoor environments.
Games with pathtracing are way ahead in the lighting department. For me Alan Wake 2 and Cyberpunk 2077 are nextgen games that already exist in the present. Games with ray tracing, lumen etc. are the games of the current generation. Nevertheless, Control was able to hide such weaknesses better.

Some ray tracing GI methods probably come much closer to pathtracing but the problem with local light sources that do not cast shadows remains. This can probably only be solved by pathtracing.

For comparison to illustrate the advantages of Pathtracing. Cyberpunk 2077 PT vs. RT

Cyberpunk 2077 PT vs.. RT - Imgsli

More screenshots

Spoiler

 

[Andrew Lauritzen]

Some ray tracing GI methods probably come much closer to pathtracing but the problem with local light sources that do not cast shadows remains. This can probably only be solved by pathtracing.

You don't need PT to do direct shadowing on local lights. You do need some sort of lighting sampling strategy. Restir is one way to do this, but has its own strengths and weakness, and there are others. I do imagine many games will start to tackle this problem next as it is definitely an area where you can significantly improve visual quality particularly for low lighting/night/indoor scenes. I expect there's probably a sweet spot somewhere between the equivalent of cyberpunk ultra RT and "overdrive" that has all lights casting shadows but with less of a performance hit than throwing it all into PT land and trying to deal with the resulting denoising (with varying levels of success). The latter is probably ok for high end PCs, but is certainly not going to be doable this generation of consoles, whereas I could see something more in the middle ground working well on today's console hardware (particularly at 30Hz).

 

[Jupiter]

It is clear that local light sources without path tracing can have shadows. I once saw a UE demo where a UE developer said that all the hundreds of light sources shown would cast shadows. Unfortunately, I don't see any of that in this game. It's disappointing to see such nice tech demos that solve the problem but don't make it into the game. In Tobocop there are many scenes with only a few light sources in the room and most don't cast any shadows.

I really hope that this problem gets more addressed in the future because it really spoils the impression. Avatar has the same problem and Cyberpunk 2077 also had it before Pathtracing. In Cyberpunk 2077 you even had to activate shadow maps next to the local RT shadows because otherwise even more light sources wouldn't cast any shadows.
Otherwise, all the games I remember have the problem with missing shadows. I've known that there are a lot of light sources since the Deferred Rendering days but the shadows are missing.

EDIT:

Could not find that video after 2 hours of searching.

In any case, the video is from this year and it showed a simple cityscape. The Epic UE programmer? placed lanterns and the more lanterns. He placed them over each other which made the light calculation more complex since the light beam collides with each BVH of every single lantern. The density of BVH objects was also displayed in the engine. The redder the area, the more computationally intensive fpor lightinh. Later he also showed light sources and how they all cast shadows.

 

[ILikeFeet]

It is clear that local light sources without path tracing can have shadows. I once saw a UE demo where a UE developer said that all the hundreds of light sources shown would cast shadows. Unfortunately, I don't see any of that in this game. It's disappointing to see such nice tech demos that solve the problem but don't make it into the game. In Tobocop there are many scenes with only a few light sources in the room and most don't cast any shadows.

I really hope that this problem gets more addressed in the future because it really spoils the impression. Avatar has the same problem and Cyberpunk 2077 also had it before Pathtracing. In Cyberpunk 2077 you even had to activate shadow maps next to the local RT shadows because otherwise even more light sources wouldn't cast any shadows.
Otherwise, all the games I remember have the problem with missing shadows. I've known that there are a lot of light sources since the Deferred Rendering days but the shadows are missing.

EDIT:

Could not find that video after 2 hours of searching.

In any case, the video is from this year and it showed a simple cityscape. The Epic UE programmer? placed lanterns and the more lanterns. He placed them over each other which made the light calculation more complex since the light beam collides with each BVH of every single lantern. The density of BVH objects was also displayed in the engine. The redder the area, the more computationally intensive fpor lightinh. Later he also showed light sources and how they all cast shadows.

sounds like Nvidia's RTXDI demonstration

 

[Jupiter]

I checked so many videos and this was almost the only one I didn't want to test. Thanks for posting. It saves me time because I probably would have kept looking today.
Very good forum. No other known forum would have been able to do anything with my description.

In this video RTXDI, RT AO, RTXGI is used and it provides you a more similar look to pathtracing. Any area light, spot light and so on is a shadow casting light.

 

[VFX_Veteran]

It is clear that local light sources without path tracing can have shadows. I once saw a UE demo where a UE developer said that all the hundreds of light sources shown would cast shadows. Unfortunately, I don't see any of that in this game. It's disappointing to see such nice tech demos that solve the problem but don't make it into the game. In Tobocop there are many scenes with only a few light sources in the room and most don't cast any shadows.

I really hope that this problem gets more addressed in the future because it really spoils the impression. Avatar has the same problem and Cyberpunk 2077 also had it before Pathtracing. In Cyberpunk 2077 you even had to activate shadow maps next to the local RT shadows because otherwise even more light sources wouldn't cast any shadows.
Otherwise, all the games I remember have the problem with missing shadows. I've known that there are a lot of light sources since the Deferred Rendering days but the shadows are missing.

EDIT:

Could not find that video after 2 hours of searching.

In any case, the video is from this year and it showed a simple cityscape. The Epic UE programmer? placed lanterns and the more lanterns. He placed them over each other which made the light calculation more complex since the light beam collides with each BVH of every single lantern. The density of BVH objects was also displayed in the engine. The redder the area, the more computationally intensive fpor lightinh. Later he also showed light sources and how they all cast shadows.

This has been my major complaint in games for years. Path-tracing will obviously solve this but I don't think it's the game engines not supporting it but the GPUs not having enough bandwidth. Even if you do a single cast for a shadow ray, you'd only be making sharp shadows. Blurred shadows would require several casts to the light sources -- which would be forced to calling the BRDF several times. It can get even more complicated with transparent surfaces for colored shadows. Add to that the world space computation of ambient occlusion on smaller objects like spoons, cups, trash, etc.. in the scene that normally gets skipped in lighting computations with screenspace approaches.

This is more likely the reason "demos" have the correct functionality compared to a full blown video game.

 

[DavidGraham]

 

[Jupiter]

It's remarkable how many high-quality videos DF can produce. This video is very important and I'm glad they made it.
And I agree it's a a shame that a well-made game like Dead Space will always be jerky. They are not making any effort to change this.

The predecessor of the Jedi game has already stuttered a lot. I don't know why these Jedi games stutter even more than other UE games.

I'm surprised at how well Avatar and Robocop run. I didn't buy Robocop at the start but the game is still new and I don't have any stutters. As we see one can also do better on the PC, Robocop perhaps stutters less because there are many individual levels. When you enter a building a black loading screen appears briefly.

This has been my major complaint in games for years. Path-tracing will obviously solve this but I don't think it's the game engines not supporting it but the GPUs not having enough bandwidth. Even if you do a single cast for a shadow ray, you'd only be making sharp shadows. Blurred shadows would require several casts to the light sources -- which would be forced to calling the BRDF several times. It can get even more complicated with transparent surfaces for colored shadows. Add to that the world space computation of ambient occlusion on smaller objects like spoons, cups, trash, etc.. in the scene that normally gets skipped in lighting computations with screenspace approaches.

This is more likely the reason "demos" have the correct functionality compared to a full blown video game.

This needs to be addressed in the future. Night scenes don't look so good especially in games with lots of light sources. Before Pathtracing, I also thought that Cyberpunk 2077 looked better during the day. At night there were too many missing shadows.

I'm almost finished with Robocop and in daytime scenes it looks surprisingly good in places.

 

[davis.anthony]

Can this thread get back to talking about DF videos?

The discussion of who is responsible for releasing games in a 'good' state also maybe deserves it's own thread.

 

[chris1515]