Physically Based Rendering

Ozzy

Ozzy

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I hope my wish is not too late, but since development of new shaders was postponed, we might have still a chance.:D


I don't think I have to explain all that much. PBR is more or less industry standard for games and CGI.
Even "small" games using inhouse engines like iRacing or DCS World come up with PBR support.

Besides the obvious advantage of more realistic materials you also get:
- More consistent materials in all scenes / lighting conditions
- More consistent and easier workflow when creating materials (which usually results in a faster workflow)

The advantages should directly transfer to modding because instead of dealing with a dozen of specular and fresnel values, you typically only adjust the roughness and IOR (which you can basically google).
I only have basic experience myself, but even as a beginner I could create some awesome looking materials in Blender Cycles. I think that already shows how awesome this must be.:p

Since rFactor 2 aims for a realistic look, PBR should be a perfect fit.

I'm curious about what others have to say. Are there any other advantages or even disadvantages using PBR?
 
No disadvantages in using PBR shaders. and indeed they are much needed.

What is important to know, though, is that having PBR shaders doesn't mean that everything will suddenly became easy and super pretty. You cited Blender Cycles, which is a ray-trace based render engine, not real time. That itself changes a lot of things. Seeing what people do with the Quixel suite (or Substance Painter) and plug into real time rendering engines such as Marmoset Toolbag is probably more informative for this matter.

Also we have to remember that in games most of the shader values end up being stored in textures. That means, if we take (the much appreciated) roughness for example, we instantly get another texture to store in VRAM.
For example: recently I did an experiment getting one of the rF2 models and loading up in Marmoset Toolbag 3 but instead of using the given textures and materials, I created new - full PBR - ones that could reproduce cars that can have matte, glossy and golden*** parts. In other words, I changed the map stored on the albedo texture's alpha channel to be the roughness, and added a new RGB texture to store the specular intensity/color. That, for a single car livery in 4K, added a 10mb on the count.

***I said golden, not chrome, because some materials, as gold, have non-grayscale specular.

P.S.: Although other sims make better use of PBR, I'm not entirely sure if they use roughness. AC doesn't seem to, maybe pCARS does. iRacing, honestly, I fail to even notice they are using PBR at all, let alone roughness.
 
Fabio Pittol said:
What is important to know, though, is that having PBR shaders doesn't mean that everything will suddenly became easy and super pretty. You cited Blender Cycles, which is a ray-trace based render engine, not real time. That itself changes a lot of things. Seeing what people do with the Quixel suite (or Substance Painter) and plug into real time rendering engines such as Marmoset Toolbag is probably more informative for this matter.
Click to expand...
That's definitely true. Realtime engines probably have to make compromises. As far as I've read, you really have to know your way around shader coding to get all the "pbr rules" implemented. Maybe IRacing only implemented a subset of them?

Fabio Pittol said:
Also we have to remember that in games most of the shader values end up being stored in textures. That means, if we take (the much appreciated) roughness for example, we instantly get another texture to store in VRAM.
For example: recently I did an experiment getting one of the rF2 models and loading up in Marmoset Toolbag 3 but instead of using the given textures and materials, I created new - full PBR - ones that could reproduce cars that can have matte, glossy and golden*** parts. In other words, I changed the map stored on the albedo texture's alpha channel to be the roughness, and added a new RGB texture to store the specular intensity/color. That, for a single car livery in 4K, added a 10mb on the count.
Click to expand...
That's indeed a disadvantage, although I'm not quite sure if it really matters, looking at the huge VRAM sizes availabe on modern GPUs. There may also be different techniques to get somewhat around this problem (different resolution maps, uber shaders, metalness workflow?). I'm wondering if games, which support tessallation actually using displacement maps? If yes, then another type of map seems to be doable. ;)

patchedupdemon said:
Iracing looks like a simpsons cartoon reguarding the flat colour detail of the the cars,the other sims do look better and if that's what pbr can do with the right devs then yeah ok
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Disney uses PBR for animated cartoons, so you still have to create realistic texture maps and feed the shaders whith realistic values to get a realistic look. I don't have IRacing myself. From what I can see on youtube it doesn't look too bad, but certainly shows a little bit of age:). DCS World 2, PCars 2 and Unreal 4 look all pretty good with PBR. Don't know if GT Sport is using it but I would bet they are.

In the end of the day, it is like with an advanced physics engine. Even if it wouldn't work better than today, it is still nice to know that it is there.:D
 
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Indeed. S397 is slowly implementing all my dream features for rF2. For such a small studio this is really remarkable.
 
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