PBR lighting issues

[Llymlaen]

I returned to SL and noticed PBR is now releases on Firestorm so I went to test things out but having an issue. Applied a default wood material in SP

As you can see in Legacy midday lighting theres lighting reflecting and creating this blue shading in the lines. Went to google and figured out I should be using Reflection probes? (the inside square)

This next picture is with using normal Midday settings. It looks better outside and within the probe.

So do I always use reflection probes on builds that are in the world? (not within walls)

Is it possible to get the Midday Legacy to look like Midday one?

The videos I watched on PBR in SL did not have these issues in their PBR materials. They uploaded theirs and it looked really nice.

Is it happening because my Occlusion/roughness/metalic is all red? (default smart material..havent adjusted the roughness/metallic channels)

Thanks!

[Tayln Osbourne]

Except for builds on ground level (and even then), you will need reflection probes. It's the cheapest solution for providing the lighting and environment data PBR requires. The non-probe solutions either are too demanding to run on integrated GPUs or require dedicated raytracing cores on GPUs.

As for substance painter, you may need to add the ambient occlusion channel to your document as none of the default shaders adds it by default.

It also looks like you are using a cube probe, which does no attempt at all to blend between the sky probe and autoprobes, and does a poor job of blending with manual probes as well. I would strongly suggest using sphere probes when you can manage it.

Edited September 1 by Nagachief Darkstone
Substance Painter info + Probe Info

[Crexon]

The new Midday is the replacement for "midday legacy" so to answer your question on making the legacy one look like it, the answer is use the non-legacy one as your reference environment. 

The new midday is as close as possible to this HDRi environment from PolyHaven. https://polyhaven.com/a/cloud_layers

You can grab an environment you can load into SP that is the new midday. https://github.com/Jenna-Huntsman/Second-Life-Resources/tree/main/PBR/HDRi

As for reflection probes I recommend checking out this Goggle doc that going over alot about reflections probes and has been super helpful for alot of people.
https://docs.google.com/document/d/18ut5mR_S9sAYDwWvFHNpRqrJ31y2hpqVSZHd8sbeua4/edit#heading=h.60c6xrs3vk7q

[ChinRey]

8 hours ago, Crexon said:

the answer is use the non-legacy one as your reference environment.

No. Sorry to say this but the new midday setting is useless. It doesn't have nearly enough ambient light and adds that annoying bluish or greenish tint to any light colored surface. If I udnerstand right, LL is working on an improvement but in the meantime we're pretty much left in limbo.

[Crexon]

41 minutes ago, ChinRey said:

No. Sorry to say this but the new midday setting is useless. It doesn't have nearly enough ambient light and adds that annoying bluish or greenish tint to any light colored surface. If I udnerstand right, LL is working on an improvement but in the meantime we're pretty much left in limbo.

No. This is per the official wiki. 

[Porky Gorky]

1 hour ago, Crexon said:

No. This is per the official wiki.

Just because it says it on a wiki doesn’t negate the fact that the default environment is not fit for purpose. The OP should search the MP for PBR compatible EEP’s

[Crexon]

32 minutes ago, Porky Gorky said:

Just because it says it on a wiki doesn’t negate the fact that the default environment is not fit for purpose. The OP should search the MP for PBR compatible EEP’s

Can you provide evidence that what it looks like in SL is different then it inside of blender for purpose of creating content?

[Tayln Osbourne]

3 hours ago, ChinRey said:

No. Sorry to say this but the new midday setting is useless. It doesn't have nearly enough ambient light and adds that annoying bluish or greenish tint to any light colored surface. If I udnerstand right, LL is working on an improvement but in the meantime we're pretty much left in limbo.

Reflection probes help somewhat with the darkness, though in interior spaces you may need to adjust the probe's individual ambience level to compensate for the lack of HDR light sources beyond the sky itself.

Your brain naturally 'ignores' the blueness in real life. But it's very much there. Here's a pretty good example of strong sunlight diffusing and bouncing off of the green grass and onto the house. You can also see the strong blue hue in the shadows caused by the gables of the house.

[Porky Gorky]

11 hours ago, Crexon said:

Can you provide evidence that what it looks like in SL is different then it inside of blender for purpose of creating content?

I think you are missing the point. Using the HDRI recommended on the wiki will allow you to author PBR Materials, (using Blender, Substance etc) that will be compatible with the default environment in SL. I am not disputing that. So your advice was technically accurate and in-line with LL’s official guidance. It is still bad advice though.

If I were to follow the official guidance (which I did) and author some PBR and bring it into the default environment, the result would be a surface that had too much blue light reflecting upon it, even on non-reflective surfaces. This is why I suggest it is not fit for purpose.

Now it could be that the default environment has a realistic level of blue, as Nagachief points out above, the sky is very blue in reality. I suspect the problem may derive from the way surfaces reflect light in SL. Reflectivity seems to be oversensitive, too much light is reflected. This can be demonstrated when we use PBR materials in SL that are authored for real PBR shaders. 

To compensate for this, some SL users have been creating EEP’s with more neutral tones which have brought us closer to the appearance of physical accuracy and many of them are now bordering on the acceptable.

I think the challenge for people creating PBR materials is to find or create an EEP that they think is acceptable for rendering PBR in SL, then find or create the closest compatible HDRI map that can be used in their authoring software.

At first, further tweaking and testing will still be required once the material is in SL, specifically customizing the roughness map to compensate for the reflectivity issue I mentioned above. Maybe tweaking the base colour to account for the ACES tone mapping if needed. However once you've customized a few materials for SL and established the requirements, you can set up a custom filter (in Substance at least) to automate that process.

Edited September 2 by Porky Gorky

[Porky Gorky]

13 hours ago, Nagachief Darkstone said:

Your brain naturally 'ignores' the blueness in real life. But it's very much there. Here's a pretty good example of strong sunlight diffusing and bouncing off of the green grass and onto the house. You can also see the strong blue hue in the shadows caused by the gables of the house.

In reality, when a photon interacts with a surface it causes the light to be absorbed, reflected, scattered, refracted etc. depending upon the properties of the surface and the intensity of the photon which can bounce off of surfaces multiple times, reducing in intensity after each bounce. This is evident in the picture you posted. For me it begs the question; how accurate is SL’s renderer at simulating this phenomena? How accurate is the simulation of light absorption, reflection, scattering and refraction? 

Edited September 2 by Porky Gorky

[Fluffy Sharkfin]

25 minutes ago, Porky Gorky said:

In reality, when a photon interacts with a surface it causes the light to be absorbed, reflected, scattered, refracted etc. depending upon the properties of the surface and the intensity of the photon which can bounce off of a surface multiple times, reducing in intensity after each bounce. This is evident in the picture you posted. For me it begs the question; how accurate is SL’s renderer at simulating this phenomena? How accurate is the simulation of light absorption, reflection, scattering and refraction? 

Those are more concerns that apply to ray tracing than PBR.  PBR deals more with object surfaces and uses predetermined formula to calculate the colour of pixels rather than relying so heavily on calculating how photons interact with the objects.  As to how accurate the implementation of PBR is in SL, the recent threads here on the forums seem to suggest "not very".

 

Footnote: The obligatory google AI explanation of the differences between PBR and ray tracing lists one of those differences as...

Quote

"PBR is used in applications such as tire treads, sportswear, and golf balls. Ray tracing is used in computer graphics, architecture, engineering, and lighting design."

(You learn something new every day, and TIL that googles AI is an imbecile!)

[Porky Gorky]

38 minutes ago, Fluffy Sharkfin said:

Those are more concerns that apply to ray tracing than PBR.  PBR deals more with object surfaces and uses predetermined formula to calculate the colour of pixels rather than relying so heavily on calculating how photons interact with the objects. 

Sure, I realise that, Nagachief posted a picture of reality (or an extremely accurate CGI render) and talked about the effect of bouncing photons. I guess my vague point was, is that image/topic even relevant to the conversation when we dissect what the SL renderer can actually do? As you pointed out, we don’t have ray tracing, we don’t have subsurface scattering, displacement, refraction, so on and so on. We do not have a rendering system anywhere near capable of simulating the effects of the photons in that image, was my point.

I must make a point of making clearer points.

[Fluffy Sharkfin]

9 minutes ago, Porky Gorky said:

Sure, I realise that, Nagachief posted a picture of reality (or an extremely accurate CGI render) and talked about the effect of bouncing photons.

Yeah I figured you already have a pretty clear understanding of the difference, I guess I just missed the point you were trying to make. 😅

I'm intrigued by the picture, mostly because I haven't seen it yet (every time I view this thread I get a pop-up warning from my antivirus software and the picture gets blocked).

 

11 minutes ago, Porky Gorky said:

I must make a point of making clearer points.

And I should probably bear in mind that there's such things as rhetorical questions and not every sentence that ends in a ? requires an answer. 🤣

[Fluffy Sharkfin]

16 minutes ago, Porky Gorky said:

We do not have a rendering system anywhere near capable of simulating the effects of the photons in that image, was my point.

Exactly!  SLs current lighting system is not ideal for PBR and due to that fact it's incredibly hard to tell just how effective their implementation of PBR materials really is.  I'm hoping that they have plans to improve things and add more control (hopefully without making things too difficult for the majority of residents to cope with) and better options when it comes to scene lighting.

As has been pointed out before by other people, implementing PBR without also implementing a suitable lighting system is ultimately self-defeating because without proper lighting you still can't achieve the realism that PBR is designed to produce.  I'm just assuming (hoping?) that LL also realise this and are working on plans to update SLs lighting as we speak?!

[Tayln Osbourne]

3 hours ago, Fluffy Sharkfin said:

Exactly!  SLs current lighting system is not ideal for PBR and due to that fact it's incredibly hard to tell just how effective their implementation of PBR materials really is.  I'm hoping that they have plans to improve things and add more control (hopefully without making things too difficult for the majority of residents to cope with) and better options when it comes to scene lighting.

As has been pointed out before by other people, implementing PBR without also implementing a suitable lighting system is ultimately self-defeating because without proper lighting you still can't achieve the realism that PBR is designed to produce.  I'm just assuming (hoping?) that LL also realise this and are working on plans to update SLs lighting as we speak?!

They are planning on adding glTF's punctual lights, which are defined in real units, instead of the 0 - 1 intensity that current lights are defined in. This allows them to go outside the SDR range and contribute the correct amount of lighting. Unfortunately, due to performance problems with the current PBR releases, they've had to pause work on glTF scenes to improve that.

5 hours ago, Fluffy Sharkfin said:

"PBR is used in applications such as tire treads, sportswear, and golf balls. Ray tracing is used in computer graphics, architecture, engineering, and lighting design."

Raytracing is rendering method, PBR is a way to define a material's properties. You don't need PBR to use Raytracing, but generally PBR has more grounded materials that would look better in a raytracer.

5 hours ago, Porky Gorky said:

For me it begs the question; how accurate is SL’s renderer at simulating this phenomena? How accurate is the simulation of light absorption, reflection, scattering and refraction? 

For outdoor scenes it does a relatively convincing job when a scene is properly probed and the object has good occlusion data. The current SSAO solution could be replaced at some point, which would reduce the need of strong occlusion bakes into PBR materials. I'm sure once properly HDR lights are introduced I'm gonna have to tweak my personal day cycles as they'll probably end up being too bright as I compensate for the lack of HDR lights by upping probe ambience overall. For example, my 'Florida Spring' daycycle uses a probe ambience of 2 during the day to make the outside properly bright.

Currently, SL only has the base glTF material rendering, so it can't do refraction. However, glTF Transmission, IOR, and Diffraction are the first planned extensions, which would introduce screen space transmission. While that wouldn't produce refracted light and caustics (because you can only do that with raytracing), it would produce much more realistic looking glass and water overall.

Light absorption isn't accurate. glTF suggests using single scatter GGX for real-time rendering. It loses energy on rough surfaces. Multi-scatter GGX fixes this, but it's much more demanding to use.