[jfrancis]

If I were using some sort of software that produced game shaders and it had a PBR option that talked about the 'metallic channel,' what would that sort of map to in Maxwell. Nothing directly, I guess, but what would be the way to think about that channel?

[luis.hijarrubia]

Reflectance 90 if that metallic is about how metallic reflection looks. Inverted Roughness if that metallic channel tells how much metallic the material is. Nothing directly, a very far aproximation anyway.

[jfrancis]

Interesting. Reflectance 90 sounds like a good general candidate since I think it already has a roughness channel.

[Half Life]

The theory is that metallic should be a hard on-or-off property -- Black or white, with the only shades of grey for anti-aliasing. In practice that may not always be true -- the treatment in Maxwell could be handled in a few ways... but probably the easiest to manage for most users would be a layer mask on a three layer material.

Base layer - Diffuse Color Textures Used: Base Color
Layer 1 - Additive "Specular" Layer for non-metallic roughness Textures Used: Roughness
Layer 2 - Normal Layer for metallic roughness (using metallic map as layer mask) Textures Used: Base Color, Roughness, Metallic

[jfrancis]

Sounds like a good idea.

[Mihai]

What would the 'Metallic Channel' be?

It's marketing. The same with "PBR" materials. I don't care if this sounds fanboy-ish but these "new" workflows is what we've been doing in Maxwell for years, or rather what the material editor has allowed us to do since the beginning. Reflected light, roughness, Nd and K, Transmittance etc...

In Maxwell you don't need to confuse yourself with this new marketing speak, what's important are the Nd and K settings for metals, to get the right intensity and fresnel for the reflections. If you only take care of the Nd, you'll get more plastic like reflections. So if you want to get a colored anodized look for example, take care to use both the Nd and K for the BSDF in the additive layer, and set them to the values of a typical aluminium, then blend/colorize to taste. Voila, you have a "PBR" workflow....

[burnin]

Base layer - Diffuse Color Textures Used: Base Color
Layer 1 - Additive "Specular" Layer for non-metallic roughness Textures Used: Roughness
Layer 2 - Normal Layer for metallic roughness (using metallic map as layer mask) Textures Used: Base Color, Roughness, Metallic

I only do it with one or two layers. Base color is not needed for metals (fully reflective), so unless there's a change in material property (ie. oxidation, rust, damage...) then i do extra layer over.

I prefer to consider PBR workflow as standardization for the game industry (RT rendering in game engines), since that's the intent of...
If and when offline render engines will pick it up, only time will tell. For time being, no one is on it's way to change.

[Half Life]

Iray is all PBR, so a major offline engine is using it: http://www.nvidia-arc.com/iray.html

As to why the terminology matters for Maxwell users: the textures are all shifting from the old Diffuse/Specular model to Metallic/Roughness... as a user we must keep up or die.

[burnin]

^Thanks for the info, and i agree on keep moving forward in unison.

[luis.hijarrubia]

Iray is all PBR, so a major offline engine is using it: http://www.nvidia-arc.com/iray.html

As to why the terminology matters for Maxwell users: the textures are all shifting from the old Diffuse/Specular model to Metallic/Roughness... as a user we must keep up or die.

Well, the diffuse / specular way of understanding materials was the default approach for real-time for many years. Maxwell never used that, maxwell have "Physically correct rendering", it's even marketed as light simulator. Many real-time engines are trying to get closer to a physically correct rendering, but that still not possible in real-time, so this kind of "physically based rendering" appeared everywhere. Iray, and many others offers that kind of pbr materials only as a proxy, when rendering offline they transform that kind of material to a more correct one. If that's a PBR material, maxwell have them: the material assistants. For example the Opaque one have "shinniness / roughness" configuration, that can be seen as a PBR material that it's internally transformed into a proper maxwell material.

So, having "correct", maxwell should not want to go to "based". Assistants can be made to help doing things easier to new people, and some kind of real-time or interactive-time rendering can be desirable, sacrificing some quality, as preview. But allway from "correct" to real-time, not from real-time assumptions. That's my way of seeing it.

[feynman]

I don't know anything about games, VR, etc.

But from rendering products, I find the way to make a material incredibly easy to use - I can look up the Nd and K or have it measured and simply type in the values, and copper looks like copper and leather looks like leather.

I believe - as is the case with the camera and lighting in MR - that materials that use values/settings that product designers can derive from reality make most sense and are easiest to understand.

My 2 Kronor ; )