PBR : Albedo, k, Gloss, k, Reflectivity, meh.

NovaaH

So yeah, I got what the albedo, and gloss right, I think, but reflectivity is posing me problems.

Metalic materials, you have a black ( Cause metal reflect most of the light. ) and a tainted reflectivity, ok. But others materials : http://www.pacocasares.com/wp-content/uploads/2014/04/graphChart.jpg

For examples, why does the leaves have a grey reflectivity map, while the Satin is colored ?

http://viewer.marmoset.co/test/gdcgallery.html ( 4th one, the black dude. )

Why are the skin pore darker than the rest of the skin ? Isn't this kind of details supposed to be in the gloss map ?.. And why his hands are purple ?

Would love if someone could clarify the use of this map for me.

Thanks in advance. \o/

Dan Powell

There's two types of Reflectivity in PBR: Metalness and Specular.

Depending on what Engine/Renderer you're using one of them will be preferred. For example, Unreal 4 prefers you use a Metalness workflow.

Metalness is a typically black and white texture map. White is metal, black is not. Some things like rust you might use a grey value for, or for when you need to transition between metals.

Specular is the same as it's always been - however you should use the PBR charts Marmoset's website provides to use correct Specular values. The key difference is that Specular Reflectivity can contain colour, Metalness cannot.

JedTheKrampus

The satin and tarp are colored because it's incorrect scan data from a prototype 3D scanner. It would look more correct if those reflectivity values were desaturated, since those are both non-metallic materials. If you look closely at the leaves you'll see that they have a bit of color in them for the same reason. You should avoid this color in textures that you make, unless it's for a metallic material and you're using the specular setup rather than the metallic setup.

The black guy has black dots in his pores to represent specular micro-occlusion that's view independent. You should generally do this whenever your model has tiny cavities like pores or wrinkles in order to bring out the detail better. You can bake a cavity map in xNormal and multiply it over the reflectivity texture you made in order to get this effect in any game engine.

NovaaH

A little late, but thanks you both for your answers. \o/

If anyone end up here looking for the same explanation I was looking for :

https://www.marmoset.co/toolbag/learn/pbr-theory
http://www.marmoset.co/toolbag/learn/pbr-practice

Those two articles helped me a lot, too.