PBR is coming...

[Quarrel Kukulcan]

22 hours ago, Wulfie Reanimator said:

The other (screen space) ambient occlusion is a dynamic effect, in the sense that separate objects can interact with each other. They'll get that darkening effect when they get close together, which cannot be done with AO maps.

Not to be overly pendantic, but just to allay some confusion... SSAO is yet another, third type of AO and has nothing to do with textures, PBR or Yseult's question. It's real, and neat, but it's its own thing.

[Wulfie Reanimator]

34 minutes ago, Quarrel Kukulcan said:

Not to be overly pendantic, but just to allay some confusion... SSAO is yet another, third type of AO and has nothing to do with textures, PBR or Yseult's question. It's real, and neat, but it's its own thing.

I figured by "AO post-processing" they meant SSAO, as in something seen in the viewer. If that's not it, what AO post-process effect are they referring to?

[Yseult UwU]

yes i meant SSAO, sorry for the confusion.

as an aside, i'm curious why there's no specular channel in the new PBR menu, how are non-metallic reflections handled?

[PekeNL]

4 hours ago, Yseult UwU said:

yes i meant SSAO, sorry for the confusion.

as an aside, i'm curious why there's no specular channel in the new PBR menu, how are non-metallic reflections handled?

Roughness for not metallic surfaces are handled by normal + roughness maps.

[Quarrel Kukulcan]

5 hours ago, Wulfie Reanimator said:

I figured by "AO post-processing" they meant SSAO, as in something seen in the viewer. If that's not it, what AO post-process effect are they referring to?

...I completely misread that that was their actual question. My bad.

I thought they were asking how the PBR AO channel results in any different rendering look than burning it into the diffuse texture yourself.

[OptimoMaximo]

15 hours ago, Yseult UwU said:

as an aside, i'm curious why there's no specular channel in the new PBR menu, how are non-metallic reflections handled?

Pbr systems do not use specularity at high level, meaning it's not exposed to user input. The point is, being Physically Based, it's handled internally from physical properties*, and it's the whole point of having a mask to mark the metallic areas as opposed to dielectric areas. What makes a visual difference, which the user has to develop for the use case at hand, is how rough the surface is.

Arguably, like the shader used in UnrealEngine, someone thought to add a greyscale "specular level" input to further modulate the energy conservation property of a material (which basically means how much of the original light bounces off the surface), which modifies the principle of absorption.

Other rendering engines add more options but those are basically just "layers" of additional specular materials, like the so called clearcoat, used to simulate the non metallic specularity of a polished car on top of the metal paint.

*the physical properties are hardcoded, because reflectance at normal and energy absorbtion is known beforehand, and they fall within two general types, metallic and non metallic (dielectric)

[hinaichigo Xaris]

I HAVE A QUESTION!

What does PBR mean?

[ChinRey]

43 minutes ago, hinaichigo Xaris said:

I HAVE A QUESTION!

What does PBR mean?

Physical Based Rendering.

It's a fundamentally different concept to texturing; rather than a texture giving the color for each point on a surface, PBR attempts to replicate the physical properties that cause a material to have its color.

Strictly speaking we don't use the term correctly in games and virtual worlds. It's still not possbile to replicate all the physical laws of RL in a real time virtual reality so PBR for us is a bit of a mix between premade textures and dynamic physical based effects. It's not actually something brand new in SL. Even the old legacy bumpiness maps and shininess effects are arguably a very primitive take on game/vritual world style PBR. What's new is that LL is taking the concept several steps further to match what more modern game/virtual world engines have to offer.

Edited February 7, 2023 by ChinRey

[Love Zhaoying]

This was just posted:

 

 

[Yseult UwU]

so if i'm understanding correctly, specular reflections are inherent in all objects, it's just the roughness map that determines how strong/weak they are?

[Frionil Fang]

Reflections are inherent in all materials, but the roughness slider determines how the reflection behaves on a sliding scale between fully diffuse (scattered, soft, no gloss) and fully specular (focused, sharp, mirror-like). Metalness also plays its part on how the light behaves.

I haven't checked out the PBR viewer specifically, but this is what you get in Blender (and the idea is that what you get in Blender/other GLTF-using PBR engines matches what you get in SL): left is roughness 0, right is roughness 1. Both are non-metallic. 

[Yseult UwU]

i see

if specular reflections are inherent in all objects, how do we control its color? with the current pre-PBR system you can use a colorful specular map to reflect specific colors, but i don't see a means to do that in this system if specular reflections are inherent and not texture defined.

Edited February 9, 2023 by Yseult UwU
misspoke

[Frionil Fang]

Specularity color is controlled by metallicity; colored speculars are "unphysical".

If the material is metallic, specular color comes from albedo; if the material is not metallic, specular is white. Technically materials that are between 0 and 1 in metallicity are not physical and don't exist in real world, but they're allowed for smooth blending for texels that are on the border, or if your material exhibits both properties on a larger scale.

This, of course, leaves processes like soap bubbles and oil slicks unanswered since they're clearly not metallic, but the typical SL/game engine PBR does not simulate iridescence or other fancy light behavior.

Edited February 9, 2023 by Frionil Fang

[Love Zhaoying]

2 minutes ago, Frionil Fang said:

Specularity color is controlled by metallicity; colored speculars are "unphysical".

If the material is metallic, specular color comes from albedo; if the material is not metallic, specular is white. Technically materials that are between 0 and 1 in metallicity are not physical and don't exist in real world, but they're allowed for smooth blending for texels that are on the border, or if your material exhibits both properties on a larger scale.

Here's one reason I LOVE these threads.  I highlighted all the "jargon".  To uneducated people like me, it's beautiful words.

[Frionil Fang]

There's certainly a lot of fancy terms when it comes to "accurate rendering" and expanding every definition (even if I knew how to) would get wordy. Unfortunately even Blender's built in shaders in the ray-tracing engine don't do the really intricate light behaviors like structural colors i.e. iridescence without cheating or combining a pile of shaders, so it's not gonna happen in real time in SL. If you want soap bubbles, you might need to go with the ol' diffuse-specular style without having metal bubbles.

Edited February 9, 2023 by Frionil Fang

[Frionil Fang]

Though as a challenge:

Specularity: the part of light that is reflected directly off the surface, like a mirror. For reasons that I probably couldn't try to explain properly (it involves quantum mechanics I think?) only metals can have colored specular reflections.

Diffuse: the part of light that is scattered off the surface, resulting in smooth lighting but no discernible "images" in the reflection.

Albedo: the wavelengths the material reflects; if the albedo is red, red is reflected, greens and blues are absorbed.

Metallicity: metals' electrical conductivity makes them reflect light in a different way (see the quantum mechanics) than non-electrically conductive materials. A material either is a metal or is not, but our rendering tricks are not strictly restricted by this.

Texel: a texture pixel; a texel does not correspond directly to a screen pixel, like if it's small enough not to be directly seen, it gets blended with others or if it's so large that it covers multiple pixels.

Iridescence: some materials don't get their colors from absorbing and reflecting wavelengths, but instead their actual microscopic structure "shifts" light in a way that results in colors emerging despite not being metals. Butterfly wings and soap bubbles do this.

Edited February 9, 2023 by Frionil Fang
typos

[Love Zhaoying]

43 minutes ago, Frionil Fang said:

Technically materials that are between 0 and 1 in metallicity are not physical and don't exist in real world

By "real world", do you actually mean "in the rendered world" (such as in Second Life), or the "real", "actual" world?

[Frionil Fang]

19 minutes ago, Love Zhaoying said:

By "real world", do you actually mean "in the rendered world" (such as in Second Life), or the "real", "actual" world?

Like real real world. Either the material has the kind of free electron movement that metals do, or doesn't. Maybe some kind of exotic polymers that conduct electricity could have metallic reflections? I actually have no idea.

I *think* the reason metals can have colored specular reflection is because the free electrons' quantum mechanical energy levels let them directly reflect some wavelengths while absorbing and not re-emitting others. This is why gold is, well, gold colored, but silver is extremely white because its absorption wavelengths are actually in the ultraviolet range; if we could see ultraviolet, we'd see silver as a distinct color and not just "white".

Edited February 9, 2023 by Frionil Fang

[ChinRey]

1 hour ago, Love Zhaoying said:

Here's one reason I LOVE these threads.  I highlighted all the "jargon".  To uneducated people like me, it's beautiful words.

All you really need to fully understand PBR are professional level 3D modelling skills and a master's degree in physics. But for those very few people who for some reason chose to dedicate their lives to pursue other paths of learning: what the metalicousionessity does is determine how much the color of the texture/albedo map/diffuse map affects the reflection/shininess. If the metalicness is low, the shine will be white, if it's high the shine will have the same color as the texture.

This is actually a cruder and more primitive solution than the one we have now where we can set surface and refelction colors separately. It's not particularly user friendly either, regardless of how well you understand PBR. But computers - who aren't even allowed to study at univiersities yet - prefer it this way and we have to be nice to them because one day they will take over the world.

Edited February 9, 2023 by ChinRey

[Frionil Fang]

Yeah fortunately you don't really need to deeply understand the "why", just what the general gist of the material settings are and how they interact.

Me, I'm not a physicist, just a nerd, and I enjoy trying to figure out the underlying principles. Note the trying part.

And fortunately, we do still have the diffuse-specular system available even after PBR hits, so if that results in materials that work for you, don't see a reason not to use it.

[benchthis]

8 hours ago, Love Zhaoying said:

This was just posted:

 

 

This was really cool introduction, me waits patiently for access to the test grid. Seems neat. After downloading Second Life Project GLTF PBR Materials 7.0.0.577997 (64b) my poor computer sounds like it's going to blow up. I had to derender water and avatars and particles and everything else to be able to get my computer to not scream. I'm not really into JIRAing anymore. But so far noticed in the main grid textures are having difficult time remaining rendered, they go in and out of being blurry to sharp. 

Fast forward a year we're going to be golden.  

[Love Zhaoying]

4 hours ago, benchthis said:

Fast forward a year we're going to be golden.  

My over-active mind says, look - that could be a "PBR Joke!" Because "golden" is a metallic "color"!

[ChinRey]

9 hours ago, benchthis said:

Fast forward a year we're going to be golden.  

Maybe, maybe not:

9 hours ago, benchthis said:

I had to derender water and avatars and particles and everything else to be able to get my computer to not scream. I'm not really into JIRAing anymore. But so far noticed in the main grid textures are having difficult time remaining rendered, they go in and out of being blurry to sharp.

No need for a JIRA. Those are known issues, listed in the release notes. But they need to be fixed or the whole project is DOA. LL seems to be confident they can but time will show.

[benchthis]

11 hours ago, Love Zhaoying said:

My over-active mind says, look - that could be a "PBR Joke!" Because "golden" is a metallic "color"!

This is taking it way too far, but maybe there can be special edition last names for the launch. Official materials last names would be neat to celebrating that milestone. Ceramic, Plastic, Platinum, Copper, Brass, Crome, to mention a few. 

Wonders how many official materials will be added to the system inventory for users to use? Or if that will be even be built in?

Maybe if there is a materials folder with goodies in the future for all, maybe an evolved notecard that can translate instructions vs having several notecards. 

 

Edited February 10, 2023 by benchthis

[benchthis]

Say I have a linden home and I have wild neighbors. I don't want to move but I wish to look out my windows and see a reflection of the official surroundings homes & landscaping. 

Will parcels have about land settings for reflection probe options that would only be seen if physically within the parcel? 

The parcel boundary would need a hollowed out rectangle with the material crome maybe dropped in to see the world outside vs world within. One panorama photo used as the image to reflect on to the surface of the rectangle. If all sides are transparent except for the internal hollow part of the rectangle would others see it from outside the parcel? 

It's little confusing. Here's video showing kind of what I mean. Notice blenders world texture is reflected onto the sphere. 

I'd like that sphere hollowed out and put around my linden home and the world texture reflected inside the sphere to create my own little world.