Materials vs. Texture Sets

I am modeling an ottoman, and need help interpreting the instructions, which say, " Amount of materials should be same as amount of texture sets. "

Some info on the model : My ottoman is one mesh, with a high-poly version baked onto a normal map. The materials are a gray mottled leather with dark wood feet. I have been provided only this texture…

enter image description here

1st question: So, a “material” is the full node set-up, and a “texture” is any of the maps or images used to plug in to that material’s nodes (or just set on the UV mapping). Is that correct? But, then, what is a "texture set "? I would think they mean the group of generated images or textural maps for each of the 9 materials they list here:

  • Main textures:
    • BaseColor (sRGB)
    • AO (Linear)
    • Roughness (Linear)
    • Metalness (Linear)
    • Normal (RGB)
    • Opacity (Linear)
    • Emissive (sRGB)
  • Additional textures: Glossiness, Specular

Here are the other relevant instructions :

  • Single UV set per model, multiple textures sets if extra resolutions is needed
  • Only square textures, 4096x4096 resolution
  • Normal maps baked from hi-poly models
  • Metalness & Specular workflow maps needed

What I would normally think to do in making a model like this is to apply a material to each part (one for the leather, one for the feet), then use a multi-noded setup for each one, including procedural texture for the basecolor, the provided texture image for bump and light-related maps (the baking of which I will be figuring out on the fly), the baked normal map I have from the high-poly mesh, plus certain settings on the Diffuse Shader.

It seems to me that this does not meet the following requirements:

Metalness & Specular workflow maps needed (This confuses me anyway, as I’ve never really heard of using every single map, and I thought Metalness & Specular were generally used one or the other. Also, can you even bake a procedural color into a image map?)

Amount of materials should be same as amount of texture sets (It seems like I will have 2 materials and something like 9 textures, so what really differentiates a texture set from a material in this context?)

Can someone set me straight, and maybe help me figure out the workflow here?

Materials: Material Slots in blender
The # Textures as materials: they mean 1 PBR set per material. Base Color, Metallic, Roughness, Normal. The difference is there are JUST textures and a basic shader. Think packing it all into a glTF, which is what it sounds like they’re going to do with it. There are no procedural nodes, color ramps, or anything.

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Does blender’s gltf exporter support specular/glossy workflow, tho?

https://docs.blender.org/manual/en/latest/addons/import_export/io_scene_gltf2.html?highlight=gltf

Metallic-roughness for export.

Very helpful answer above, thank you.
Now that it’s been brought up, though, I did need to address just that: the Metalness/Roughness vs Specular/Glossy issue. So the Principled BSDF Shader has a Metallic and a Specular input, and also a Roughness input. On the Glossy, I guess I’ll have to use the Glossy BSDF node?
And additionally, sirmaxim, since you seem to have an understanding of their specs and reasoning… Do they really mean for me to generate texture maps for each of the inputs, even though they’re usually one or the other? Would I plug in all image nodes at once, and will that work fine?
And I guess, then, using the glTF (I had to look it up), the only nodes they will want are the Principled BSDF, the image texture nodes, and (I guess?) the Glossy BSDF?
Does that seem about right, or have I missed anything?

No glossy BSDF. You don’t need it with the Principled BSDF.

You should read up on the textures and how they compare to previous texturing methods: https://marmoset.co/posts/pbr-texture-conversion/

There are two PBR workflows. In Blender it is easy to get unrealistic light bounces with specular (most surfaces fall very close to .5), so it’s more an artistic adjustment.

Ideally, you’ll want to know what the renderer they’re using is and be able to test it so you know you’re delivering what you see.