PBR Textures questions

3 PBR questions. My understanding is that there are 2 types of PBR material workflows. Those using SpecGloss and those using MetallicRoughness.

However in the PBR MAT there are slots for both Specular and Metallic and Roughness.

Is there a reason or scenario when you might want to have all slots defined? Or if you are defining a Specular Level Map should you leave Metallic and Roughness undefined?

If you have both albedo AND diffuse maps should you use albedo with PBR materials?

If you have a gloss map where would that be slotted, Roughness or?

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Great questions! Would love to hear some official feedback on these as well. + 1

I personally leave specular out, and just use metallic / rough, but I do notice a slight change when I do stuff with specular, in addition to metal/rough. Not sure what the meaning of that is though.

I think albedo is another term for diffuse if I’m not mistaken? I believe the map’s purpose regardless of it’s name is to provide surface color info with as little lighting and shadowing information mixed in as possible. Like how stuff looks on a cloudy day etc.

Not 100% sure about gloss, would love to hear other thoughts there, but my understanding is that does not play a part in the pbr model touch has. I think some shader authors may include the maps necessary for the older shading model that works with gloss, so their sbar is more “backwards compatible”, but could totally be wrong about that.

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Started studying PBR topic and ran into the same questions.

Maybe I found the answer to that one here. In Substance MetalRough workflow it is normally assumed that all dielectrics 4% reflective and this value for them is usually not defined separately. However, it can be overridden with Specular Level map: “Some metal/roughness implementations, such as those found in the Substance toolset and Unreal Engine 4, have a specular control, which allows the artist to change the constant F0 value for dielectrics. In Substance, this output is labeled as ‘‘specularLevel’’”. So I guess you would normally want to leave Specular Level map empty, unless you have weird dielectrics that have weird reflectance values.

Glossiness I figure shouldn’t go to Roughness because in theory those maps are opposite of each other. So I got the same feeling as Lucas - probably PBR implementation of TD does not support SpecGloss workflow.

But definitely it would be nice to have more on these questions in the Wiki :slight_smile:

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